Deborah M Gordon

All Publications

• Colony life history of the tropical arboreal ant, Cephalotes goniodontus De Andrade, 1999. Insectes sociaux Butler, I. A., Butterfield, T., Janda, M., Gordon, D. M. 2024; 71 (3): 271-281

  Abstract

  Arboreal ants are ecologically important in tropical forests, but there are few studies using DNA markers to examine their population and colony structure. Colonies of the arboreal turtle ant Cephalotes goniodontus create trail networks through the canopy of the tropical forest, in dense vegetation where it is difficult to determine how long a nest is used and how neighboring colonies partition space. We monitored 53 nest sites for up to six years and, using seven microsatellite markers, genotyped samples of workers collected at or near 41 nests over 1-4 years. We calculated average relatedness within samples collected at a given location, and between samples collected at the same location in successive years, and performed pedigree analysis to predict the number of queens that produced each sample of workers. Fifteen samples were highly related (r ≥ 0.6) from single colonies, of which 11 were monogynous and the remaining four had two queens; 19 were of intermediate relatedness (0.1 ≤ r < 0.6) with 1-6 queens, and 7 were groups of unrelated workers (r < 0.1) from at least 4 queens. Colonies persisted at the same nest site for 2-6 years. The smallest distance we found separating nests of different colonies was 16.2 m. It appears that different colonies may share foraging trails. Our study demonstrates the feasibility of using a cost-efficient genotyping method to provide information on colony structure and life history of ant species.The online version contains supplementary material available at 10.1007/s00040-024-00974-3.

  View details for DOI 10.1007/s00040-024-00974-3

  View details for PubMedID 39286752

  View details for PubMedCentralID PMC11401787

• Colony life history of the tropical arboreal ant, <i>Cephalotes goniodontus</i> De Andrade, 1999 INSECTES SOCIAUX Butler, I. E., Butterfield, T., Janda, M., Gordon, D. M. 2024

  View details for DOI 10.1007/s00040-024-00974-3

  View details for Web of Science ID 001258023000001

• Harvester ant colonies differ in collective behavioural plasticity to regulate water loss. Royal Society open science Gordon, D. M., Steiner, E., Das, B., Walker, N. S. 2023; 10 (9): 230726

  Abstract

  Collective behavioural plasticity allows ant colonies to adjust to changing conditions. The red harvester ant (Pogonomyrmex barbatus), a desert seed-eating species, regulates foraging activity in response to water stress. Foraging ants lose water to evaporation. Reducing foraging activity in dry conditions sacrifices food intake but conserves water. Within a year, some colonies tend to reduce foraging on dry days while others do not. We examined whether these differences among colonies in collective behavioural plasticity persist from year to year. Colonies live 20-30 years with a single queen who produces successive cohorts of workers which live only a year. The humidity level at which all colonies tend to reduce foraging varies from year to year. Longitudinal observations of 95 colonies over 5 years between 2016 and 2021 showed that differences among colonies, in how they regulate foraging activity in response to day-to-day changes in humidity, persist across years. Approximately 40% of colonies consistently reduced foraging activity, year after year, on days with low daily maximum relative humidity; approximately 20% of colonies never did, foraging as much or more on dry days as on humid days. This variation among colonies may allow evolutionary rescue from drought due to climate change.

  View details for DOI 10.1098/rsos.230726

  View details for PubMedID 37736532

• Biological rhythms and task allocation in ant colonies. Current opinion in insect science Das, B., Gordon, D. M. 2023: 101062

  Abstract

  Task allocation in ant colonies, mediated by social interactions, regulates which individuals perform each task, and when they are active, in response to the current situation. Many tasks are performed in a daily temporal pattern. An ant's biological clock depends on patterns of gene expression that are regulated using a negative feedback loop which is synchronized to earth's rotation by external cues. An individual's biological clock can shift in response to social cues, and this plasticity contributes to task switching. Daily rhythms in individual ant behavior combine, via interactions within and across task groups, to adjust the collective behavior of colonies. Further work is needed to elucidate how the social cues that lead to task switching influence the molecular mechanisms that generate clock outputs associated with each task, and to investigate the evolution of temporal patterns in task allocation in relation to ecological factors.

  View details for DOI 10.1016/j.cois.2023.101062

  View details for PubMedID 37247773

• Collective behavior in relation with changing environments: Dynamics, modularity, and agency. Evolution & development Gordon, D. M. 2023

  Abstract

  Collective behavior operates without central control, using local interactions among participants to adjust to changing conditions. Many natural systems operate collectively, and by specifying what objectives are met by the system, the idea of agency helps to describe how collective behavior is embedded in the conditions it deals with. Ant colonies function collectively, and the enormous diversity of more than 15K species of ants, in different habitats, provides opportunities to look for general ecological patterns in how collective behavior operates. The foraging behavior of harvester ants in the desert regulates activity to manage water loss, while the trail networks of turtle ants in the canopy tropical forest respond to rapidly changing resources and vegetation. These examples illustrate some broad correspondences in natural systems between the dynamics of collective behavior and the dynamics of the surroundings. To outline how interactions among participants, acting in relation with changing surroundings, achieve collective outcomes, I focus on three aspects of collective behavior: the rate at which interactions adjust to conditions, the feedback regime that stimulates and inhibits activity, and the modularity of the network of interactions. To characterize the dynamics of the surroundings, I consider gradients in stability, energy flow, and the distribution of resources and demands. I then propose some hypotheses that link how collective behavior operates with changing environments.

  View details for DOI 10.1111/ede.12439

  View details for PubMedID 37190859

• Modeling collective cell behavior in cancer: Perspectives from an interdisciplinary conversation. Cell systems Adler, F. R., Anderson, A. R., Bhushan, A., Bogdan, P., Bravo-Cordero, J. J., Brock, A., Chen, Y., Cukierman, E., DelGiorno, K. E., Denis, G. V., Ferrall-Fairbanks, M. C., Gartner, Z. J., Germain, R. N., Gordon, D. M., Hunter, G., Jolly, M. K., Karacosta, L. G., Mythreye, K., Katira, P., Kulkarni, R. P., Kutys, M. L., Lander, A. D., Laughney, A. M., Levine, H., Lou, E., Lowenstein, P. R., Masters, K. S., Pe'er, D., Peyton, S. R., Platt, M. O., Purvis, J. E., Quon, G., Richer, J. K., Riddle, N. C., Rodriguez, A., Snyder, J. C., Lee Szeto, G., Tomlin, C. J., Yanai, I., Zervantonakis, I. K., Dueck, H. 2023; 14 (4): 252-257

  Abstract

  Collective cell behavior contributes to all stages of cancer progression. Understanding how collective behavior emerges through cell-cell interactions and decision-making will advance our understanding of cancer biology and provide new therapeutic approaches. Here, we summarize an interdisciplinary discussion on multicellular behavior in cancer, draw lessons from other scientific disciplines, and identify future directions.

  View details for DOI 10.1016/j.cels.2023.03.002

  View details for PubMedID 37080161

• Distributed algorithms from arboreal ants for the shortest path problem. Proceedings of the National Academy of Sciences of the United States of America Garg, S., Shiragur, K., Gordon, D. M., Charikar, M. 2023; 120 (6): e2207959120

  Abstract

  Colonies of the arboreal turtle ant create networks of trails that link nests and food sources on the graph formed by branches and vines in the canopy of the tropical forest. Ants put down a volatile pheromone on the edges as they traverse them. At each vertex, the next edge to traverse is chosen using a decision rule based on the current pheromone level. There is a bidirectional flow of ants around the network. In a previous field study, it was observed that the trail networks approximately minimize the number of vertices, thus solving a variant of the popular shortest path problem without any central control and with minimal computational resources. We propose a biologically plausible model, based on a variant of the reinforced random walk on a graph, which explains this observation and suggests surprising algorithms for the shortest path problem and its variants. Through simulations and analysis, we show that when the rate of flow of ants does not change, the dynamics converges to the path with the minimum number of vertices, as observed in the field. The dynamics converges to the shortest path when the rate of flow increases with time, so the colony can solve the shortest path problem merely by increasing the flow rate. We also show that to guarantee convergence to the shortest path, bidirectional flow and a decision rule dividing the flow in proportion to the pheromone level are necessary, but convergence to approximately short paths is possible with other decision rules.

  View details for DOI 10.1073/pnas.2207959120

  View details for PubMedID 36716366

• Critical thermal limits and temperature-dependent walking speed may mediate coexistence between the native winter ant (Prenolepis imparis) and the invasive Argentine ant (Linepithemahumile). Journal of thermal biology Nelson, R. A., MacArthur-Waltz, D. J., Gordon, D. M. 2023; 111: 103392

  Abstract

  Comparing the thermal tolerance and performance of native and invasive species from varying climatic origins may explain why some native and invasive species can coexist. We compared the thermal niches of an invasive and native ant species. The Argentine ant (Linepithema humile) is an invasive species that has spread to Mediterranean climates worldwide, where it is associated with losses in native arthropod biodiversity. In northern California, long-term surveys of ant biodiversity have shown that the winter ant (Prenolepis imparis) is the native species best able to coexist with Argentine ants. Both species tend hemipteran scales for food, and previous research suggests that these species' coexistence may depend on seasonal partitioning: winter ants are active primarily in the colder winter months, while Argentine ants are active primarily in the warmer months in northern California. We investigated the physiological basis of seasonal partitioning in Argentine and winter ants by a) measuring critical thermal limits, and b) comparing how ant walking speed varies with temperature. While both species had similar CTmax values, we found differences between the two species' critical thermal minima that may allow winter ants to remain functional at ecologically relevant temperatures between 0 and 2.5°C. We also found that winter ants' walking speeds are significantly less temperature-dependent than those of Argentine ants. Winter ants walk faster than Argentine ants at low temperatures, which may allow the winter ants to remain active and forage at lower winter temperatures. These results suggest that partitioning based on differences in temperature tolerance promotes the winter ant's continued occupation of areas invaded by the Argentine ant.

  View details for DOI 10.1016/j.jtherbio.2022.103392

  View details for PubMedID 36585081

• The red harvester ant. Nature methods Gordon, D. M. 2022; 19 (11): 1324-1325

  View details for DOI 10.1038/s41592-022-01671-4

  View details for PubMedID 36329275

• Rainfall, neighbors, and foraging: The dynamics of a population of red harvester ant colonies 1988-2019 ECOLOGICAL MONOGRAPHS Sundaram, M., Steiner, E., Gordon, D. M. 2022

  View details for DOI 10.1002/ecm.1503

  View details for Web of Science ID 000755443300001

• Individual Variation Does Not Regulate Foraging Response to Humidity in Harvester Ant Colonies FRONTIERS IN ECOLOGY AND EVOLUTION Nova, N., Pagliara, R., Gordon, D. M. 2022; 9

  View details for DOI 10.3389/fevo.2021.756204

  View details for Web of Science ID 000750047300001

• Better tired than lost: Turtle ant trail networks favor coherence over short edges. PLoS computational biology Chandrasekhar, A., Marshall, J. A., Austin, C., Navlakha, S., Gordon, D. M. 2021; 17 (10): e1009523

  Abstract

  Creating a routing backbone is a fundamental problem in both biology and engineering. The routing backbone of the trail networks of arboreal turtle ants (Cephalotes goniodontus) connects many nests and food sources using trail pheromone deposited by ants as they walk. Unlike species that forage on the ground, the trail networks of arboreal ants are constrained by the vegetation. We examined what objectives the trail networks meet by comparing the observed ant trail networks with networks of random, hypothetical trail networks in the same surrounding vegetation and with trails optimized for four objectives: minimizing path length, minimizing average edge length, minimizing number of nodes, and minimizing opportunities to get lost. The ants' trails minimized path length by minimizing the number of nodes traversed rather than choosing short edges. In addition, the ants' trails reduced the opportunity for ants to get lost at each node, favoring nodes with 3D configurations most likely to be reinforced by pheromone. Thus, rather than finding the shortest edges, turtle ant trail networks take advantage of natural variation in the environment to favor coherence, keeping the ants together on the trails.

  View details for DOI 10.1371/journal.pcbi.1009523

  View details for PubMedID 34673768

• Movement, Encounter Rate, and Collective Behavior in Ant Colonies. Annals of the Entomological Society of America Gordon, D. M. 2021; 114 (5): 541-546

  Abstract

  Spatial patterns of movement regulate many aspects of social insect behavior, because how workers move around, and how many are there, determines how often they meet and interact. Interactions are usually olfactory; for example, in ants, by means of antennal contact in which one worker assesses the cuticular hydrocarbons of another. Encounter rates may be a simple outcome of local density: a worker experiences more encounters, the more other workers there are around it. This means that encounter rate can be used as a cue for overall density even though no individual can assess global density. Encounter rate as a cue for local density regulates many aspects of social insect behavior, including collective search, task allocation, nest choice, and traffic flow. As colonies grow older and larger, encounter rates change, which leads to changes in task allocation. Nest size affects local density and movement patterns, which influences encounter rate, so that nest size and connectivity influence colony behavior. However, encounter rate is not a simple function of local density when individuals change their movement in response to encounters, thus influencing further encounter rates. Natural selection on the regulation of collective behavior can draw on variation within and among colonies in the relation of movement patterns, encounter rate, and response to encounters.

  View details for DOI 10.1093/aesa/saaa036

  View details for PubMedID 34512857

• Tree Preference and Temporal Activity Patterns for a Native Ant Community in an Urbanized California Woodland JOURNAL OF INSECT BEHAVIOR MacArthur-Waltz, D. J., Nelson, R. A., Lee, G., Gordon, D. M. 2021

  View details for DOI 10.1007/s10905-021-09778-w

  View details for Web of Science ID 000687937200001

• Multi-year drought exacerbates long-term effects of climate on an invasive ant species. Ecology Couper, L. I., Sanders, N. J., Heller, N. E., Gordon, D. M. 2021: e03476

  Abstract

  Invasive species threaten biodiversity, ecosystem function, and human health, but the long-term drivers of invasion dynamics remain poorly understood. We use data from a 28-year ongoing survey of a Northern California ant community invaded by the Argentine ant (Linepithema humile) to investigate the influence of abiotic and biotic factors on invasion dynamics. We found that the distribution of L. humile retracted following an extreme drought that occurred in the region from 2012 - 2015. The distribution of several native ant species also contracted, but overall native ant diversity was higher after the drought and for some native ant species, distributions expanded over the 28-year survey period. Using structural equation models, we found the strongest impact on the distribution of L. humile was from direct effects of climate, namely cumulative precipitation and summer maximum temperatures, with only a negligible role for biotic resistance and indirect effects of climate mediated by native ants. The increasing drought and high temperature extremes projected for northern California due to anthropogenic driven climate change may limit the spread, and possibly the impact, of L. humile in invaded regions. The outcome will depend on the response of native ant communities to these climatic stressors.

  View details for DOI 10.1002/ecy.3476

  View details for PubMedID 34346070

• Goals and Limitations of Modeling Collective Behavior in Biological Systems FRONTIERS IN PHYSICS Ouellette, N. T., Gordon, D. M. 2021; 9

  View details for DOI 10.3389/fphy.2021.687823

  View details for Web of Science ID 000667045200001

• Variation and change in behavior: a comment on Loftus et al. BEHAVIORAL ECOLOGY Gordon, D. M. 2021; 32 (1): 21–22

  View details for DOI 10.1093/beheco/araa116

  View details for Web of Science ID 000637013400005

• Measurement of natural variation of neurotransmitter tissue content in red harvester ant brains among different colonies. Analytical and bioanalytical chemistry Shin, M. n., Friedman, D. A., Gordon, D. M., Venton, B. J. 2020

  Abstract

  Colonies of the red harvester ant, Pogonomyrmex barbatus, regulate foraging activity based on food availability and local conditions. Colony variation in foraging behavior is thought to be linked to biogenic amine signaling and metabolism. Measurements of differences in neurotransmitters have not been made among ant colonies in a natural environment. Here, for the first time, we quantified tissue content of 4 biogenic amines (dopamine, serotonin, octopamine, and tyramine) in single forager brains from 9 red harvester ant colonies collected in the field. Capillary electrophoresis coupled with fast-scan cyclic voltammetry (CE-FSCV) was used to separate and detect the amines in individual ant brains. Low levels of biogenic amines were detected using field-amplified sample stacking by preparing a single brain tissue sample in acetonitrile and perchloric acid. The method provides low detection limits: 1 nM for dopamine, 2 nM for serotonin, 5 nM for octopamine, and 4 nM for tyramine. Overall, the content of dopamine (47 ± 9 pg/brain) was highest, followed by octopamine (36 ± 10 pg/brain), serotonin (20 ± 4 pg/brain), and tyramine (14 ± 3 pg/brain). Relative standard deviations were high, but there was less variation within a colony than among colonies, so the neurotransmitter content of each colony might change with environmental conditions. This study demonstrates that CE-FSCV is a useful method for investigating natural variation in neurotransmitter content in single ant brains and could be useful for future studies correlating tissue content with colony behavior such as foraging. Graphical abstract.

  View details for DOI 10.1007/s00216-019-02355-3

  View details for PubMedID 31912181

• Gene expression variation in the brains of harvester ant foragers is associated with collective behavior. Communications biology Friedman, D. A., York, R. A., Hilliard, A. T., Gordon, D. M. 2020; 3 (1): 100

  Abstract

  Natural selection on collective behavior acts on variation among colonies in behavior that is associated with reproductive success. In the red harvester ant (Pogonomyrmex barbatus), variation among colonies in the collective regulation of foraging in response to humidity is associated with colony reproductive success. We used RNA-seq to examine gene expression in the brains of foragers in a natural setting. We find that colonies differ in the expression of neurophysiologically-relevant genes in forager brains, and a fraction of these gene expression differences are associated with two colony traits: sensitivity of foraging activity to humidity, and forager brain dopamine to serotonin ratio. Loci that were correlated with colony behavioral differences were enriched in neurotransmitter receptor signaling & metabolic functions, tended to be more central to coexpression networks, and are evolving under higher protein-coding sequence constraint. Natural selection may shape colony foraging behavior through variation in gene expression.

  View details for DOI 10.1038/s42003-020-0813-8

  View details for PubMedID 32139795

• Editorial: An Ecological Perspective on Decision-Making: Empirical and Theoretical Studies in Natural and Natural-Like Environments FRONTIERS IN ECOLOGY AND EVOLUTION El Hady, A., Davidson, J. D., Gordon, D. M. 2019; 7

  View details for DOI 10.3389/fevo.2019.00461

  View details for Web of Science ID 000535829400001

• Cancer Ecology and Evolution: Positive interactions and system vulnerability. Current opinion in systems biology Adler, F. R., Gordon, D. M. 2019; 17: 1–7

  Abstract

  Parallels of cancer with ecology and evolution have provided new insights into the initiation and spread of cancer, and new approaches to therapy. This review describes those parallels while emphasizing some key contrasts. We argue that cancers are less like invasive species than like native species or even crops that have escaped control, and that ecological control and homeo-static control differ fundamentally through both their ends and their means. From our focus on the role of positive interactions in control processes, we introduce a novel mathematical modeling framework that tracks how individual cell lineages arise, and how the many layers of control break down in the emergence of cancer. The next generation of therapies must continue to look beyond cancers as being created by individual renegade cells and address not only the network of interactions those cells inhabit, but the evolutionary logic that created those interactions and their intrinsic vulnerability.

  View details for DOI 10.1016/j.coisb.2019.09.001

  View details for PubMedID 32318644

• Distributed Adaptive Search in T Cells: Lessons From Ants FRONTIERS IN IMMUNOLOGY Moses, M. E., Cannon, J. L., Gordon, D. M., Forrest, S. 2019; 10

  View details for DOI 10.3389/fimmu.2019.01357

  View details for Web of Science ID 000471909300001

• Distributed Adaptive Search in T Cells: Lessons From Ants. Frontiers in immunology Moses, M. E., Cannon, J. L., Gordon, D. M., Forrest, S. 2019; 10: 1357

  Abstract

  There are striking similarities between the strategies ant colonies use to forage for food and immune systems use to search for pathogens. Searchers (ants and cells) use the appropriate combination of random and directed motion, direct and indirect agent-agent interactions, and traversal of physical structures to solve search problems in a variety of environments. An effective immune response requires immune cells to search efficiently and effectively for diverse types of pathogens in different tissues and organs, just as different species of ants have evolved diverse search strategies to forage effectively for a variety of resources in a variety of habitats. Successful T cell search is required to initiate the adaptive immune response in lymph nodes and to eradicate pathogens at sites of infection in peripheral tissue. Ant search strategies suggest novel predictions about T cell search. In both systems, the distribution of targets in time and space determines the most effective search strategy. We hypothesize that the ability of searchers to sense and adapt to dynamic targets and environmental conditions enhances search effectiveness through adjustments to movement and communication patterns. We also suggest that random motion is a more important component of search strategies than is generally recognized. The behavior we observe in ants reveals general design principles and constraints that govern distributed adaptive search in a wide variety of complex systems, particularly the immune system.

  View details for DOI 10.3389/fimmu.2019.01357

  View details for PubMedID 31263465

  View details for PubMedCentralID PMC6585175

• The physiology of forager hydration and variation among harvester ant (Pogonomyrmex barbatus) colonies in collective foraging behavior SCIENTIFIC REPORTS Friedman, D. A., Greene, M. J., Gordon, D. M. 2019; 9

  View details for DOI 10.1038/s41598-019-41586-3

  View details for Web of Science ID 000462298600013

• The physiology of forager hydration and variation among harvester ant (Pogonomyrmex barbatus) colonies in collective foraging behavior. Scientific reports Friedman, D. A., Greene, M. J., Gordon, D. M. 2019; 9 (1): 5126

  Abstract

  Ants are abundant in desiccating environments despite their high surface area to volume ratios and exposure to harsh conditions outside the nest. Red harvester ant (Pogonomyrmex barbatus) colonies must spend water to obtain water: colonies lose water as workers forage outside the nest, and gain water metabolically through seeds collected in foraging trips. Here we present field experiments showing that hydrated P. barbatus foragers made more foraging trips than unhydrated nestmates. The positive effect of hydration on foraging activity is stronger as the risk of desiccation increases. Desiccation tests showed that foragers of colonies that reduce foraging in dry conditions are more sensitive to water loss, losing water and motor coordination more rapidly in desiccating conditions, than foragers of colonies that do not reduce foraging in dry conditions. Desiccation tolerance is also associated with colony reproductive success. Surprisingly, foragers that are more sensitive to water loss are from colonies more likely to produce offspring colonies. This could be because the foragers of these colonies conserve water with a more cautious response to desiccation risk. An ant's hydration status may influence its response to the olfactory interactions that regulate its decision to leave the nest to forage. Thus variation among ant colonies in worker physiology and response to ambient conditions may contribute to ecologically significant differences among colonies in collective behavior.

  View details for PubMedID 30914705

• The Ecology of Collective Behavior in Ants ANNUAL REVIEW OF ENTOMOLOGY, VOL 64 Gordon, D. M., Douglas, A. E. 2019; 64: 35–50

  View details for DOI 10.1146/annurev-ento-011118-111923

  View details for Web of Science ID 000456391400003

• Measuring collective behavior: an ecological approach. Theory in biosciences = Theorie in den Biowissenschaften Gordon, D. M. 2019

  Abstract

  Collective behavior is ubiquitous throughout nature. Many systems, from brains to ant colonies, work without central control. Collective behavior is regulated by interactions among the individual participants such as neurons or ants. Interactions create feedback that produce the outcome, the behavior that we observe: Brains think and remember, ant colonies collect food or move nests, flocks of birds turn, human societies develop new forms of social organization. But the processes by which interactions produce outcomes are as diverse as the behavior itself. Just as convergent evolution has led to organs, such as the eye, that are similar in function but are based on different physiological processes, so it has led to forms of collective behavior that appear similar but arise from different social processes. An ecological perspective can help us to understand the dynamics of collective behavior and how it works.

  View details for DOI 10.1007/s12064-019-00302-5

  View details for PubMedID 31559539

• Regulation of harvester ant foraging as a closed-loop excitable system. PLoS computational biology Pagliara, R., Gordon, D. M., Leonard, N. E. 2018; 14 (12): e1006200

  Abstract

  Ant colonies regulate activity in response to changing conditions without using centralized control. Desert harvester ant colonies forage for seeds, and regulate foraging to manage a tradeoff between spending and obtaining water. Foragers lose water while outside in the dry air, but ants obtain water by metabolizing the fats in the seeds they eat. Previous work shows that the rate at which an outgoing forager leaves the nest depends on its recent rate of brief antennal contacts with incoming foragers carrying food. We examine how this process can yield foraging rates that are robust to uncertainty and responsive to temperature and humidity across minute-to-hour timescales. To explore possible mechanisms, we develop a low-dimensional analytical model with a small number of parameters that captures observed foraging behavior. The model uses excitability dynamics to represent response to interactions inside the nest and a random delay distribution to represent foraging time outside the nest. We show how feedback from outgoing foragers returning to the nest stabilizes the incoming and outgoing foraging rates to a common value determined by the volatility of available foragers. The model exhibits a critical volatility above which there is sustained foraging at a constant rate and below which foraging stops. To explain how foraging rates adjust to temperature and humidity, we propose that foragers modify their volatility after they leave the nest and become exposed to the environment. Our study highlights the importance of feedback in the regulation of foraging activity and shows how modulation of volatility can explain how foraging activity responds to conditions and varies across colonies. Our model elucidates the role of feedback across many timescales in collective behavior, and may be generalized to other systems driven by excitable dynamics, such as neuronal networks.

  View details for PubMedID 30513076

• The Ecology of Collective Behavior in Ants. Annual review of entomology Gordon, D. M. 2018

  Abstract

  Nest choice in Temnothorax spp.; task allocation and the regulation of activity in Pheidole dentata, Pogonomyrmex barbatus, and Atta spp.; and trail networks in Monomorium pharaonis and Cephalotes goniodontus all provide examples of correspondences between the dynamics of the environment and the dynamics of collective behavior. Some important aspects of the dynamics of the environment include stability, the threat of rupture or disturbance, the ratio of inflow and outflow of resources or energy, and the distribution of resources. These correspond to the dynamics of collective behavior, including the extent of amplification, how feedback instigates and inhibits activity, and the extent to which the interactions that provide the information to regulate behavior are local or spatially centralized. Expected final online publication date for the Annual Review of Entomology Volume 64 is January 7, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  View details for PubMedID 30256667

• The Role of Dopamine in the Collective Regulation of Foraging in Harvester Ants. iScience Friedman, D. A., Pilko, A., Skowronska-Krawczyk, D., Krasinska, K., Parker, J. W., Hirsh, J., Gordon, D. M. 2018

  Abstract

  Colonies of the red harvester ant (Pogonomyrmex barbatus) differ in how they regulate collective foraging activity in response to changes in humidity. We used transcriptomic, physiological, and pharmacological experiments to investigate the molecular basis of this ecologically important variation in collective behavior among colonies. RNA sequencing of forager brain tissue showed an association between colony foraging activity and differential expression of transcripts related to biogenic amine and neurohormonal metabolism and signaling. In field experiments, pharmacological increases in forager brain dopamine titer caused significant increases in foraging activity. Colonies that were naturally most sensitive to humidity were significantly more responsive to the stimulatory effect of exogenous dopamine. In addition, forager brain tissue significantly varied among colonies in biogenic amine content. Neurophysiological variation among colonies associated with individual forager sensitivity to humidity may reflect the heritable molecular variation on which natural selection acts to shape the collective regulation of foraging.

  View details for PubMedID 30270022

• A distributed algorithm to maintain and repair the trail networks of arboreal ants. Scientific reports Chandrasekhar, A. n., Gordon, D. M., Navlakha, S. n. 2018; 8 (1): 9297

  Abstract

  We study how the arboreal turtle ant (Cephalotes goniodontus) solves a fundamental computing problem: maintaining a trail network and finding alternative paths to route around broken links in the network. Turtle ants form a routing backbone of foraging trails linking several nests and temporary food sources. This species travels only in the trees, so their foraging trails are constrained to lie on a natural graph formed by overlapping branches and vines in the tangled canopy. Links between branches, however, can be ephemeral, easily destroyed by wind, rain, or animal movements. Here we report a biologically feasible distributed algorithm, parameterized using field data, that can plausibly describe how turtle ants maintain the routing backbone and find alternative paths to circumvent broken links in the backbone. We validate the ability of this probabilistic algorithm to circumvent simulated breaks in synthetic and real-world networks, and we derive an analytic explanation for why certain features are crucial to improve the algorithm's success. Our proposed algorithm uses fewer computational resources than common distributed graph search algorithms, and thus may be useful in other domains, such as for swarm computing or for coordinating molecular robots.

  View details for PubMedID 29915325

  View details for PubMedCentralID PMC6006367

• Foraging behavior and locomotion of the invasive Argentine ant from winter aggregations. PloS one Burford, B. P., Lee, G., Friedman, D. A., Brachmann, E., Khan, R., MacArthur-Waltz, D. J., McCarty, A. D., Gordon, D. M. 2018; 13 (8): e0202117

  Abstract

  The collective behavior of ant colonies, and locomotion of individuals within a colony, both respond to changing conditions. The invasive Argentine ant (Linepithema humile) thrives in Mediterranean climates with hot, dry summers and colder, wet winters. However, its foraging behavior and locomotion has rarely been studied in the winter. We examined how the foraging behavior of three distinct L. humile colonies was related to environmental conditions and the locomotion of workers during winter in northern California. We found that colonies foraged most between 10 and 15°C, regardless of the maximum daily temperature. Worker walking speed was positively associated with temperature (range 6-24°C) and negatively associated with humidity (range 25-93%RH). All colonies foraged during all day and night hours in a predictable daily cycle, with a correlation between the rate of incoming and outgoing foragers. Foraging activity was unrelated to the activity of a competing native ant species, Prenolepis imparis, which was present in low abundance, and ceased only during heavy rain when ants left foraging trails and aggregated in small sheltered areas on trees.

  View details for PubMedID 30092038

• Local Regulation of Trail Networks of the Arboreal Turtle Ant, Cephalotes goniodontus AMERICAN NATURALIST Gordon, D. M. 2017; 190 (6): E156–E169

  Abstract

  This study examines how an arboreal ant colony maintains, extends, and repairs its network of foraging trails and nests, built on a network of vegetation. Nodes are junctions where a branch forks off from another or where a branch of one plant touching another provides a new edge on which ants could travel. The ants' choice of edge at a node appears to be reinforced by trail pheromone. Ongoing pruning of the network tends to eliminate cycles and minimize the number of nodes and thus decision points, but not the distance traveled. At junctions, trails tend to stay on the same plant. In combination with the long internode lengths of the branches of vines in the tropical dry forest, this facilitates travel to food sources at the canopy edge. Exploration, when ants leave the trail on an edge that is not being used, makes both search and repair possible. The fewer the junctions between a location and the main trail, the more likely the ants are to arrive there. Ruptured trails are rapidly repaired with a new path, apparently using breadth-first search. The regulation of the network promotes its resilience and continuity.

  View details for DOI 10.1086/693418

  View details for Web of Science ID 000415995200003

  View details for PubMedID 29166159

• Spatial organization and interactions of harvester ants during foraging activity JOURNAL OF THE ROYAL SOCIETY INTERFACE Davidson, J. D., Gordon, D. M. 2017; 14 (135)

  Abstract

  Local interactions, when individuals meet, can regulate collective behaviour. In a system without any central control, the rate of interaction may depend simply on how the individuals move around. But interactions could in turn influence movement; individuals might seek out interactions, or their movement in response to interaction could influence further interaction rates. We develop a general framework to address these questions, using collision theory to establish a baseline expected rate of interaction based on proximity. We test the models using data from harvester ant colonies. A colony uses feedback from interactions inside the nest to regulate foraging activity. Potential foragers leave the nest in response to interactions with returning foragers with food. The time series of interactions and local density of ants show how density hotspots lead to interactions that are clustered in time. A correlated random walk null model describes the mixing of potential and returning foragers. A model from collision theory relates walking speed and spatial proximity with the probability of interaction. The results demonstrate that although ants do not mix homogeneously, trends in interaction patterns can be explained simply by the walking speed and local density of surrounding ants.

  View details for PubMedID 28978748

  View details for PubMedCentralID PMC5665826

• Two lineages that need each other. Molecular ecology Gordon, D. M., Friedman, D. A. 2017; 26 (4): 975-976

  View details for DOI 10.1111/mec.13964

  View details for PubMedID 28239928

• The Evolution of the Algorithms for Collective Behavior CELL SYSTEMS Gordon, D. M. 2016; 3 (6): 514-520

  Abstract

  Collective behavior is the outcome of a network of local interactions. Here, I consider collective behavior as the result of algorithms that have evolved to operate in response to a particular environment and physiological context. I discuss how algorithms are shaped by the costs of operating under the constraints that the environment imposes, the extent to which the environment is stable, and the distribution, in space and time, of resources. I suggest that a focus on the dynamics of the environment may provide new hypotheses for elucidating the algorithms that produce the collective behavior of cellular systems.

  View details for DOI 10.1016/j.cels.2016.10.013

  View details for Web of Science ID 000395782800006

  View details for PubMedID 28009263

• Effect of Interactions between Harvester Ants on Forager Decisions. Frontiers in ecology and evolution Davidson, J. D., Arauco-Aliaga, R. P., Crow, S., Gordon, D. M., Goldman, M. S. 2016; 4

  Abstract

  Harvester ant colonies adjust their foraging activity to day-to-day changes in food availability and hour-to-hour changes in environmental conditions. This collective behavior is regulated through interactions, in the form of brief antennal contacts, between outgoing foragers and returning foragers with food. Here we consider how an ant, waiting in the entrance chamber just inside the nest entrance, uses its accumulated experience of interactions to decide whether to leave the nest to forage. Using videos of field observations, we tracked the interactions and foraging decisions of ants in the entrance chamber. Outgoing foragers tended to interact with returning foragers at higher rates than ants that returned to the deeper nest and did not forage. To provide a mechanistic framework for interpreting these results, we develop a decision model in which ants make decisions based upon a noisy accumulation of individual contacts with returning foragers. The model can reproduce core trends and realistic distributions for individual ant interaction statistics, and suggests possible mechanisms by which foraging activity may be regulated at an individual ant level.

  View details for DOI 10.3389/fevo.2016.00115

  View details for PubMedID 28758093

  View details for PubMedCentralID PMC5531068

• Context-dependent expression of the foraging gene in field colonies of ants: the interacting roles of age, environment and task. Proceedings. Biological sciences / The Royal Society Ingram, K. K., Gordon, D. M., Friedman, D. A., Greene, M., Kahler, J., Peteru, S. 2016; 283 (1837)

  Abstract

  Task allocation among social insect workers is an ideal framework for studying the molecular mechanisms underlying behavioural plasticity because workers of similar genotype adopt different behavioural phenotypes. Elegant laboratory studies have pioneered this effort, but field studies involving the genetic regulation of task allocation are rare. Here, we investigate the expression of the foraging gene in harvester ant workers from five age- and task-related groups in a natural population, and we experimentally test how exposure to light affects foraging expression in brood workers and foragers. Results from our field study show that the regulation of the foraging gene in harvester ants occurs at two time scales: levels of foraging mRNA are associated with ontogenetic changes over weeks in worker age, location and task, and there are significant daily oscillations in foraging expression in foragers. The temporal dissection of foraging expression reveals that gene expression changes in foragers occur across a scale of hours and the level of expression is predicted by activity rhythms: foragers have high levels of foraging mRNA during daylight hours when they are most active outside the nests. In the experimental study, we find complex interactions in foraging expression between task behaviour and light exposure. Oscillations occur in foragers following experimental exposure to 13 L : 11 D (LD) conditions, but not in brood workers under similar conditions. No significant differences were seen in foraging expression over time in either task in 24 h dark (DD) conditions. Interestingly, the expression of foraging in both undisturbed field and experimentally treated foragers is also significantly correlated with the expression of the circadian clock gene, cycle Our results provide evidence that the regulation of this gene is context-dependent and associated with both ontogenetic and daily behavioural plasticity in field colonies of harvester ants. Our results underscore the importance of assaying temporal patterns in behavioural gene expression and suggest that gene regulation is an integral mechanism associated with behavioural plasticity in harvester ants.

  View details for DOI 10.1098/rspb.2016.0841

  View details for PubMedID 27581876

  View details for PubMedCentralID PMC5013789

• From division of labor to the collective behavior of social insects BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY Gordon, D. M. 2016; 70 (7): 1101-1108

  View details for DOI 10.1007/s00265-015-2045-3

  View details for Web of Science ID 000378871700012

• The behavioral ecology of variation in social insects. Current opinion in insect science Jandt, J. M., Gordon, D. M. 2016; 15: 40-4

  Abstract

  Understanding the ecological relevance of variation within and between colonies has been an important and recurring theme in social insect research. Recent research addresses the genomic and physiological factors and fitness effects associated with behavioral variation, within and among colonies, in regulation of activity, cognitive abilities, and aggression. Behavioral variation among colonies has consequences for survival and reproductive success that are the basis for evolutionary change.

  View details for DOI 10.1016/j.cois.2016.02.012

  View details for PubMedID 27436730

• Experimental modulation of external microbiome affects nestmate recognition in harvester ants (Pogonomyrmex barbatus). PeerJ Dosmann, A., Bahet, N., Gordon, D. M. 2016; 4: e1566

  Abstract

  Social insects use odors as cues for a variety of behavioral responses, including nestmate recognition. Past research on nestmate recognition indicates cuticular hydrocarbons are important nestmate discriminators for social insects, but other factors are likely to contribute to colony-specific odors. Here we experimentally tested whether external microbes contribute to nestmate recognition in red harvester ants (Pogonomyrmex barbatus). We changed the external microbiome of ants through topical application of either antibiotics or microbial cultures. We then observed behavior of nestmates when treated ants were returned to the nest. Ants whose external microbiome was augmented with microbial cultures were much more likely to be rejected than controls, but ants treated with antibiotics were not. This result is consistent with the possibility that external microbes are used for nestmate recognition.

  View details for DOI 10.7717/peerj.1566

  View details for PubMedID 26855857

  View details for PubMedCentralID PMC4741111

• Ant Genetics: Reproductive Physiology, Worker Morphology, and Behavior ANNUAL REVIEW OF NEUROSCIENCE, VOL 39 Friedman, D. A., Gordon, D. M. 2016; 39: 41-56

  Abstract

  Many exciting studies have begun to elucidate the genetics of the morphological and physiological diversity of ants, but as yet few studies have investigated the genetics of ant behavior directly. Ant genomes are marked by extreme rates of gene turnover, especially in gene families related to olfactory communication, such as the synthesis of cuticular hydrocarbons and the perception of environmental semiochemicals. Transcriptomic and epigenetic differences are apparent between reproductive and sterile females, males and females, and workers that differ in body size. Quantitative genetic approaches suggest heritability of task performance, and population genetic studies indicate a genetic association with reproductive status in some species. Gene expression is associated with behavior including foraging, response to queens attempting to join a colony, circadian patterns of task performance, and age-related changes of task. Ant behavioral genetics needs further investigation of the feedback between individual-level physiological changes and socially mediated responses to environmental conditions.

  View details for DOI 10.1146/annurev-neuro-070815-013927

  View details for Web of Science ID 000381633400003

  View details for PubMedID 27050321

• The evolution of the algorithms for collective behavior Cell Systems Gordon, D. M. 2016: 514-52-

  View details for DOI 10.1016/j.cels.2016.10.013

• From division of labor to the collective behavior of social insects. Behavioral ecology and sociobiology Gordon, D. M. 2015; 70: 1101-1108

  Abstract

  'Division of labor' is a misleading way to describe the organization of tasks in social insect colonies, because there is little evidence for persistent individual specialization in task. Instead, task allocation in social insects occurs through distributed processes whose advantages, such as resilience, differ from those of division of labor, which are mostly based on learning. The use of the phrase 'division of labor' persists for historical reasons, and tends to focus attention on differences among individuals in internal attributes. This focus distracts from the main questions of interest in current research, which require an understanding of how individuals interact with each other and their environments. These questions include how colony behavior is regulated, how the regulation of colony behavior develops over the lifetime of a colony, what are the sources of variation among colonies in the regulation of behavior, and how the collective regulation of colony behavior evolves.

  View details for DOI 10.1007/s00265-015-2045-3

  View details for PubMedID 27397966

  View details for PubMedCentralID PMC4917577

• Interactions Increase Forager Availability and Activity in Harvester Ants PLOS ONE Pless, E., Queirolo, J., Pinter-Wollman, N., Crow, S., Allen, K., Mathur, M. B., Gordon, D. M. 2015; 10 (11)

  View details for DOI 10.1371/journal.pone.0141971

  View details for PubMedID 26539724

• Intermediate disturbance promotes invasive ant abundance BIOLOGICAL CONSERVATION Vonshak, M., Gordon, D. M. 2015; 186: 359-367

  View details for DOI 10.1016/j.biocon.2015.03.024

  View details for Web of Science ID 000355061300040

• Distributed nestmate recognition in ants PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Esponda, F., Gordon, D. M. 2015; 282 (1806)

  Abstract

  We propose a distributed model of nestmate recognition, analogous to the one used by the vertebrate immune system, in which colony response results from the diverse reactions of many ants. The model describes how individual behaviour produces colony response to non-nestmates. No single ant knows the odour identity of the colony. Instead, colony identity is defined collectively by all the ants in the colony. Each ant responds to the odour of other ants by reference to its own unique decision boundary, which is a result of its experience of encounters with other ants. Each ant thus recognizes a particular set of chemical profiles as being those of non-nestmates. This model predicts, as experimental results have shown, that the outcome of behavioural assays is likely to be variable, that it depends on the number of ants tested, that response to non-nestmates changes over time and that it changes in response to the experience of individual ants. A distributed system allows a colony to identify non-nestmates without requiring that all individuals have the same complete information and helps to facilitate the tracking of changes in cuticular hydrocarbon profiles, because only a subset of ants must respond to provide an adequate response.

  View details for DOI 10.1098/rspb.2014.2838

  View details for Web of Science ID 000353351000007

  View details for PubMedID 25833853

  View details for PubMedCentralID PMC4426612

• The ecology of collective behaviour PLoS Biology Gordon, D. M. 2014

  View details for DOI 10.1371/1001805

• The invasive Argentine ant Linepithema humile (Hymenoptera: Formicidae) in Northern California reserves: from foraging behavior to local spread MYRMECOLOGICAL NEWS Gordon, D. M., Heller, N. E. 2014; 19: 103-110

  View details for Web of Science ID 000330821700012

• Does an ecological advantage produce the asymmetric lineage ratio in a harvester ant population? Oecologia Gordon, D. M., Pilko, A., De Bortoli, N., Ingram, K. K. 2013; 173 (3): 849-857

  Abstract

  In dependent-lineage harvester ant populations, two lineages interbreed but are genetically distinct. The offspring of a male and queen of the same lineage are female reproductives; the offspring of a male and queen of different lineages are workers. Geographic surveys have shown asymmetries in the ratio of the two lineages in many harvester ant populations, which may be maintained by an ecological advantage to one of the lineages. Using census data from a long-term study of a dependent-lineage population of the red harvester ant, Pogonomyrmex barbatus, we identified the lineage of 130 colonies sampled in 1997-1999, ranging in age from 1 to 19 years when collected, and 268 colonies sampled in 2010, ranging in age from 1 to 28 years when collected. The ratio of lineages in the study population is similar across an 11-year interval, 0.59 J2 in 1999 and 0.66 J2 in 2010. The rare lineage, J1, had a slightly but significantly higher number of mates of the opposite lineage than the common lineage, J2, and, using data from previous work on reproductive output, higher male production. Mature colonies of the two lineages did not differ in nest mound size, foraging activity, or the propensity to relocate their nests. There were no strong differences in the relative recruitment or survivorship of the two lineages. Our results show no ecological advantage for either lineage, indicating that differences between the lineages in sex ratio allocation may be sufficient to maintain the current asymmetry of the lineage ratio in this population.

  View details for DOI 10.1007/s00442-013-2690-z

  View details for PubMedID 23715745

• Water stress strengthens mutualism among ants, trees, and scale insects. PLoS biology Pringle, E. G., Akçay, E., Raab, T. K., Dirzo, R., Gordon, D. M. 2013; 11 (11)

  Abstract

  Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.

  View details for DOI 10.1371/journal.pbio.1001705

  View details for PubMedID 24223521

  View details for PubMedCentralID PMC3818173

• Protection Mutualisms and the Community: Geographic Variation in an Ant-Plant Symbiosis and the Consequences for Herbivores SOCIOBIOLOGY Pringle, E. G., GORDON, D. M. 2013; 60 (3): 242-251

  View details for Web of Science ID 000328228600006

• Fast and Flexible: Argentine Ants Recruit from Nearby Trails PLOS ONE Flanagan, T. P., Pinter-Wollman, N. M., Moses, M. E., Gordon, D. M. 2013; 8 (8)

  Abstract

  Argentine ants (Linepithema humile) live in groups of nests connected by trails to each other and to stable food sources. In a field study, we investigated whether some ants recruit directly from established, persistent trails to food sources, thus accelerating food collection. Our results indicate that Argentine ants recruit nestmates to food directly from persistent trails, and that the exponential increase in the arrival rate of ants at baits is faster than would be possible if recruited ants traveled from distant nests. Once ants find a new food source, they walk back and forth between the bait and sometimes share food by trophallaxis with nestmates on the trail. Recruiting ants from nearby persistent trails creates a dynamic circuit, like those found in other distributed systems, which facilitates a quick response to changes in available resources.

  View details for DOI 10.1371/journal.pone.0070888

  View details for Web of Science ID 000323221500044

  View details for PubMedID 23967129

• Harvester ants use interactions to regulate forager activation and availability ANIMAL BEHAVIOUR Pinter-Wollman, N., Bala, A., Merrell, A., Queirolo, J., Stumpe, M. C., Holmes, S., Gordon, D. M. 2013; 86 (1): 197-207

  Abstract

  Social groups balance flexibility and robustness in their collective response to environmental changes using feedback between behavioural processes that operate at different timescales. Here we examine how behavioural processes operating at two timescales regulate the foraging activity of colonies of the harvester ant, Pogonomyrmex barbatus, allowing them to balance their response to food availability and predation. Previous work showed that the rate at which foragers return to the nest with food influences the rate at which foragers leave the nest. To investigate how interactions inside the nest link the rates of returning and outgoing foragers, we observed outgoing foragers inside the nest in field colonies using a novel observation method. We found that the interaction rate experienced by outgoing foragers inside the nest corresponded to forager return rate, and that the interactions of outgoing foragers were spatially clustered. Activation of a forager occurred on the timescale of seconds: a forager left the nest 3-8 s after a substantial increase in interactions with returning foragers. The availability of outgoing foragers to become activated was adjusted on the timescale of minutes: when forager return was interrupted for more than 4-5 min, available foragers waiting near the nest entrance went deeper into the nest. Thus, forager activation and forager availability both increased with the rate at which foragers returned to the nest. This process was checked by negative feedback between forager activation and forager availability. Regulation of foraging activation on the timescale of seconds provides flexibility in response to fluctuations in food abundance, whereas regulation of forager availability on the timescale of minutes provides robustness in response to sustained disturbance such as predation.

  View details for DOI 10.1016/j.anbehav.2013.05.012

  View details for Web of Science ID 000321758700026

  View details for PubMedCentralID PMC3767282

• Harvester ants use interactions to regulate forager activation and availability. Animal behaviour Pinter-Wollman, N., Bala, A., Merrell, A., Queirolo, J., Stumpe, M. C., Holmes, S., Gordon, D. M. 2013; 86 (1): 197-207

  Abstract

  Social groups balance flexibility and robustness in their collective response to environmental changes using feedback between behavioural processes that operate at different timescales. Here we examine how behavioural processes operating at two timescales regulate the foraging activity of colonies of the harvester ant, Pogonomyrmex barbatus, allowing them to balance their response to food availability and predation. Previous work showed that the rate at which foragers return to the nest with food influences the rate at which foragers leave the nest. To investigate how interactions inside the nest link the rates of returning and outgoing foragers, we observed outgoing foragers inside the nest in field colonies using a novel observation method. We found that the interaction rate experienced by outgoing foragers inside the nest corresponded to forager return rate, and that the interactions of outgoing foragers were spatially clustered. Activation of a forager occurred on the timescale of seconds: a forager left the nest 3-8 s after a substantial increase in interactions with returning foragers. The availability of outgoing foragers to become activated was adjusted on the timescale of minutes: when forager return was interrupted for more than 4-5 min, available foragers waiting near the nest entrance went deeper into the nest. Thus, forager activation and forager availability both increased with the rate at which foragers returned to the nest. This process was checked by negative feedback between forager activation and forager availability. Regulation of foraging activation on the timescale of seconds provides flexibility in response to fluctuations in food abundance, whereas regulation of forager availability on the timescale of minutes provides robustness in response to sustained disturbance such as predation.

  View details for DOI 10.1016/j.anbehav.2013.05.012

  View details for PubMedID 24031094

  View details for PubMedCentralID PMC3767282

• The rewards of restraint in the collective regulation of foraging by harvester ant colonies NATURE Gordon, D. M. 2013; 498 (7452): 91-?

  Abstract

  Collective behaviour, arising from local interactions, allows groups to respond to changing conditions. Long-term studies have shown that the traits of individual mammals and birds are associated with their reproductive success, but little is known about the evolutionary ecology of collective behaviour in natural populations. An ant colony operates without central control, regulating its activity through a network of local interactions. This work shows that variation among harvester ant (Pogonomyrmex barbatus) colonies in collective response to changing conditions is related to variation in colony lifetime reproductive success in the production of offspring colonies. Desiccation costs are high for harvester ants foraging in the desert. More successful colonies tend to forage less when conditions are dry, and show relatively stable foraging activity when conditions are more humid. Restraint from foraging does not compromise a colony's long-term survival; colonies that fail to forage at all on many days survive as long, over the colony's 20-30-year lifespan, as those that forage more regularly. Sensitivity to conditions in which to reduce foraging activity may be transmissible from parent to offspring colony. These results indicate that natural selection is shaping the collective behaviour that regulates foraging activity, and that the selection pressure, related to climate, may grow stronger if the current drought in their habitat persists.

  View details for DOI 10.1038/nature12137

  View details for Web of Science ID 000319947800039

  View details for PubMedID 23676676

• Colony life history and lifetime reproductive success of red harvester ant colonies JOURNAL OF ANIMAL ECOLOGY Ingram, K. K., Pilko, A., Heer, J., Gordon, D. M. 2013; 82 (3): 540-550

  View details for DOI 10.1111/1365-2656.12036

  View details for Web of Science ID 000317863400006

• Aggression is task dependent in the red harvester ant (Pogonomyrmex barbatus) BEHAVIORAL ECOLOGY Sturgis, S. J., Gordon, D. M. 2013; 24 (2): 532-539

  View details for DOI 10.1093/beheco/ars194

  View details for Web of Science ID 000317472000032

• Interactions with Combined Chemical Cues Inform Harvester Ant Foragers' Decisions to Leave the Nest in Search of Food PLOS ONE Greene, M. J., Pinter-Wollman, N., Gordon, D. M. 2013; 8 (1)

  Abstract

  Social insect colonies operate without central control or any global assessment of what needs to be done by workers. Colony organization arises from the responses of individuals to local cues. Red harvester ants (Pogonomyrmex barbatus) regulate foraging using interactions between returning and outgoing foragers. The rate at which foragers return with seeds, a measure of food availability, sets the rate at which outgoing foragers leave the nest on foraging trips. We used mimics to test whether outgoing foragers inside the nest respond to the odor of food, oleic acid, the odor of the forager itself, cuticular hydrocarbons, or a combination of both with increased foraging activity. We compared foraging activity, the rate at which foragers passed a line on a trail, before and after the addition of mimics. The combination of both odors, those of food and of foragers, is required to stimulate foraging. The addition of blank mimics, mimics coated with food odor alone, or mimics coated with forager odor alone did not increase foraging activity. We compared the rates at which foragers inside the nest interacted with other ants, blank mimics, and mimics coated with a combination of food and forager odor. Foragers inside the nest interacted more with mimics coated with combined forager/seed odors than with blank mimics, and these interactions had the same effect as those with other foragers. Outgoing foragers inside the nest entrance are stimulated to leave the nest in search of food by interacting with foragers returning with seeds. By using the combined odors of forager cuticular hydrocarbons and of seeds, the colony captures precise information, on the timescale of seconds, about the current availability of food.

  View details for DOI 10.1371/journal.pone.0052219

  View details for Web of Science ID 000313429800013

  View details for PubMedID 23308106

  View details for PubMedCentralID PMC3540075

• Harvester ant colony variation in foraging activity and response to humidity. PloS one Gordon, D. M., Dektar, K. N., Pinter-Wollman, N. 2013; 8 (5)

  Abstract

  Collective behavior is produced by interactions among individuals. Differences among groups in individual response to interactions can lead to ecologically important variation among groups in collective behavior. Here we examine variation among colonies in the foraging behavior of the harvester ant, Pogonomyrmex barbatus. Previous work shows how colonies regulate foraging in response to food availability and desiccation costs: the rate at which outgoing foragers leave the nest depends on the rate at which foragers return with food. To examine how colonies vary in response to humidity and in foraging rate, we performed field experiments that manipulated forager return rate in 94 trials with 17 colonies over 3 years. We found that the effect of returning foragers on the rate of outgoing foragers increases with humidity. There are consistent differences among colonies in foraging activity that persist from year to year.

  View details for DOI 10.1371/journal.pone.0063363

  View details for PubMedID 23717415

  View details for PubMedCentralID PMC3662670

• Anternet: The regulation of harvester ant foraging and Internet congestion control 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton) Prabhakar, B., Dektar, K. N., Gordon, D. M. IEEE. 2013: 1355–1359

  View details for Web of Science ID 000320654000184

• Modeling the spread of the Argentine ant into natural areas: Habitat suitability and spread from neighboring sites ECOLOGICAL MODELLING Fitzgerald, K., Heller, N., Gordon, D. M. 2012; 247: 262-272

  View details for DOI 10.1016/j.ecolmodel.2012.07.036

  View details for Web of Science ID 000313089600024

• The Dynamics of Foraging Trails in the Tropical Arboreal Ant Cephalotes goniodontus PLOS ONE Gordon, D. M. 2012; 7 (11)

  Abstract

  The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4-8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony's trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest.

  View details for DOI 10.1371/journal.pone.0050472

  View details for Web of Science ID 000312601700074

  View details for PubMedID 23209749

  View details for PubMedCentralID PMC3509047

• Plant defense, herbivory, and the growth of Cordia alliodora trees and their symbiotic Azteca ant colonies OECOLOGIA Pringle, E. G., Dirzo, R., Gordon, D. M. 2012; 170 (3): 677-685

  Abstract

  The effects of herbivory on plant fitness are integrated over a plant's lifetime, mediated by ontogenetic changes in plant defense, tolerance, and herbivore pressure. In symbiotic ant-plant mutualisms, plants provide nesting space and food for ants, and ants defend plants against herbivores. The benefit to the plant of sustaining the growth of symbiotic ant colonies depends on whether defense by the growing ant colony outpaces the plant's growth in defendable area and associated herbivore pressure. These relationships were investigated in the symbiotic mutualism between Cordia alliodora trees and Azteca pittieri ants in a Mexican tropical dry forest. As ant colonies grew, worker production remained constant relative to ant-colony size. As trees grew, leaf production increased relative to tree size. Moreover, larger trees hosted lower densities of ants, suggesting that ant-colony growth did not keep pace with tree growth. On leaves with ants experimentally excluded, herbivory per unit leaf area increased exponentially with tree size, indicating that larger trees experienced higher herbivore pressure per leaf area than smaller trees. Even with ant defense, herbivory increased with tree size. Therefore, although larger trees had larger ant colonies, ant density was lower in larger trees, and the ant colonies did not provide sufficient defense to compensate for the higher herbivore pressure in larger trees. These results suggest that in this system the tree can decrease herbivory by promoting ant-colony growth, i.e., sustaining space and food investment in ants, as long as the tree continues to grow.

  View details for DOI 10.1007/s00442-012-2340-x

  View details for Web of Science ID 000309866200009

  View details for PubMedID 22562422

• Nest site and weather affect the personality of harvester ant colonies BEHAVIORAL ECOLOGY Pinter-Wollman, N., Gordon, D. M., Holmes, S. 2012; 23 (5): 1022-1029

  Abstract

  Environmental conditions and physical constraints both influence an animal's behavior. We investigate whether behavioral variation among colonies of the black harvester ant, Messor andrei, remains consistent across foraging and disturbance situations and ask whether consistent colony behavior is affected by nest site and weather. We examined variation among colonies in responsiveness to food baits and to disturbance, measured as a change in numbers of active ants, and in the speed with which colonies retrieved food and removed debris. Colonies differed consistently, across foraging and disturbance situations, in both responsiveness and speed. Increased activity in response to food was associated with a smaller decrease in response to alarm. Speed of retrieving food was correlated with speed of removing debris. In all colonies, speed was greater in dry conditions, reducing the amount of time ants spent outside the nest. While a colony occupied a certain nest site, its responsiveness was consistent in both foraging and disturbance situations, suggesting that nest structure influences colony personality.

  View details for DOI 10.1093/beheco/ars066

  View details for Web of Science ID 000308228200017

  View details for PubMedCentralID PMC3431114

• Nest site and weather affect the personality of harvester ant colonies. Behavioral ecology : official journal of the International Society for Behavioral Ecology Pinter-Wollman, N., Gordon, D. M., Holmes, S. 2012; 23 (5): 1022-1029

  Abstract

  Environmental conditions and physical constraints both influence an animal's behavior. We investigate whether behavioral variation among colonies of the black harvester ant, Messor andrei, remains consistent across foraging and disturbance situations and ask whether consistent colony behavior is affected by nest site and weather. We examined variation among colonies in responsiveness to food baits and to disturbance, measured as a change in numbers of active ants, and in the speed with which colonies retrieved food and removed debris. Colonies differed consistently, across foraging and disturbance situations, in both responsiveness and speed. Increased activity in response to food was associated with a smaller decrease in response to alarm. Speed of retrieving food was correlated with speed of removing debris. In all colonies, speed was greater in dry conditions, reducing the amount of time ants spent outside the nest. While a colony occupied a certain nest site, its responsiveness was consistent in both foraging and disturbance situations, suggesting that nest structure influences colony personality.

  View details for DOI 10.1093/beheco/ars066

  View details for PubMedID 22936841

  View details for PubMedCentralID PMC3431114

• The Regulation of Ant Colony Foraging Activity without Spatial Information PLOS COMPUTATIONAL BIOLOGY Prabhakar, B., Dektar, K. N., Gordon, D. M. 2012; 8 (8)

  Abstract

  Many dynamical networks, such as the ones that produce the collective behavior of social insects, operate without any central control, instead arising from local interactions among individuals. A well-studied example is the formation of recruitment trails in ant colonies, but many ant species do not use pheromone trails. We present a model of the regulation of foraging by harvester ant (Pogonomyrmex barbatus) colonies. This species forages for scattered seeds that one ant can retrieve on its own, so there is no need for spatial information such as pheromone trails that lead ants to specific locations. Previous work shows that colony foraging activity, the rate at which ants go out to search individually for seeds, is regulated in response to current food availability throughout the colony's foraging area. Ants use the rate of brief antennal contacts inside the nest between foragers returning with food and outgoing foragers available to leave the nest on the next foraging trip. Here we present a feedback-based algorithm that captures the main features of data from field experiments in which the rate of returning foragers was manipulated. The algorithm draws on our finding that the distribution of intervals between successive ants returning to the nest is a Poisson process. We fitted the parameter that estimates the effect of each returning forager on the rate at which outgoing foragers leave the nest. We found that correlations between observed rates of returning foragers and simulated rates of outgoing foragers, using our model, were similar to those in the data. Our simple stochastic model shows how the regulation of ant colony foraging can operate without spatial information, describing a process at the level of individual ants that predicts the overall foraging activity of the colony.

  View details for DOI 10.1371/journal.pcbi.1002670

  View details for Web of Science ID 000308553500045

  View details for PubMedID 22927811

  View details for PubMedCentralID PMC3426560

• Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics MOLECULAR ECOLOGY Pringle, E. G., Ramirez, S. R., Bonebrake, T. C., Gordon, D. M., Dirzo, R. 2012; 21 (14): 3576-3592

  Abstract

  The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.

  View details for DOI 10.1111/j.1365-294X.2012.05618.x

  View details for Web of Science ID 000306087100017

  View details for PubMedID 22646059

• Effects of Vegetation Cover, Presence of a Native Ant Species, and Human Disturbance on Colonization by Argentine Ants CONSERVATION BIOLOGY Fitzgerald, K., Gordon, D. M. 2012; 26 (3): 525-538

  Abstract

  The spread of non-native invasive species is affected by human activity, vegetation cover, weather, and interaction with native species. We analyzed data from a 17-year study of the distribution of the non-native Argentine ant (Linepithema humile) and the native winter ant (Prenolepis imparis) in a preserve in northern California (U.S.A.). We conducted logistic regressions and used model selection to determine whether the following variables were associated with changes in the distribution of each species: presence of conspecifics at neighboring sites, distance to development (e.g., roads, buildings, and landscaped areas), proportion of vegetation cover taller than 0.75 m, elevation, distance to water, presence of both species at a site, temperature, and rainfall. Argentine ants colonized unoccupied sites from neighboring sites, but the probability of appearance and persistence decreased as distance to development, vegetation cover, and elevation increased. Winter ants appeared and persisted in sites with relatively high vegetation cover (i.e., highly shaded sites). Presence of the 2 species was negatively associated in sites with high vegetation cover (more winter ants) and sites near development (more Argentine ants). Probability of colonization of Argentine ants decreased where winter ants were most persistent. At sites near development within the preserve, abundant Argentine ant populations may be excluding winter ants. The high abundance of Argentine ants at these sites may be due to immigration from suburban areas outside the preserve, which are high-quality habitat for Argentine ants. In the interior of the preserve, distance from development, low-quality habitat, and interaction with winter ants may in combination exclude Argentine ants. Interactions among the variables we examined were associated with low probabilities of Argentine ant colonization in the preserve.

  View details for DOI 10.1111/j.1523-1739.2012.01836.x

  View details for Web of Science ID 000304135300016

  View details for PubMedID 22533673

• Nestmate recognition in ants (Hymenoptera: Formicidae): a review MYRMECOLOGICAL NEWS Sturgis, S. J., Gordon, D. M. 2012; 16: 101-110

  View details for Web of Science ID 000299801000014

• The effect of individual variation on the structure and function of interaction networks in harvester ants JOURNAL OF THE ROYAL SOCIETY INTERFACE Pinter-Wollman, N., Wollman, R., Guetz, A., Holmes, S., Gordon, D. M. 2011; 8 (64): 1562-1573

  Abstract

  Social insects exhibit coordinated behaviour without central control. Local interactions among individuals determine their behaviour and regulate the activity of the colony. Harvester ants are recruited for outside work, using networks of brief antennal contacts, in the nest chamber closest to the nest exit: the entrance chamber. Here, we combine empirical observations, image analysis and computer simulations to investigate the structure and function of the interaction network in the entrance chamber. Ant interactions were distributed heterogeneously in the chamber, with an interaction hot-spot at the entrance leading further into the nest. The distribution of the total interactions per ant followed a right-skewed distribution, indicating the presence of highly connected individuals. Numbers of ant encounters observed positively correlated with the duration of observation. Individuals varied in interaction frequency, even after accounting for the duration of observation. An ant's interaction frequency was explained by its path shape and location within the entrance chamber. Computer simulations demonstrate that variation among individuals in connectivity accelerates information flow to an extent equivalent to an increase in the total number of interactions. Individual variation in connectivity, arising from variation among ants in location and spatial behaviour, creates interaction centres, which may expedite information flow.

  View details for DOI 10.1098/rsif.2011.0059

  View details for Web of Science ID 000295211200003

  View details for PubMedID 21490001

  View details for PubMedCentralID PMC3177612

• Twitter in the Ant Nest How does a colony organize its work? NATURAL HISTORY Gordon, D. M. 2011; 119 (6): 10-?

  View details for Web of Science ID 000209462400008

• Hydrocarbons on Harvester Ant (Pogonomyrmex barbatus) Middens Guide Foragers to the Nest JOURNAL OF CHEMICAL ECOLOGY Sturgis, S. J., Greene, M. J., Gordon, D. M. 2011; 37 (5): 514-524

  Abstract

  Colony-specific cuticular hydrocarbons are used by social insects in nestmate recognition. Here, we showed that hydrocarbons found on the mound of Pogonomyrmex barbatus nests facilitate the return of foragers to the nest. Colony-specific hydrocarbons, which ants use to distinguish nestmates from non-nestmates, are found on the midden pebbles placed on the nest mound. Midden hydrocarbons occur in a concentration gradient, growing stronger near the nest entrance, which is in the center of a 1-2 m diameter nest mound. Foraging behavior was disrupted when the gradient of hydrocarbons was altered experimentally. When midden material was diluted with artificial pebbles lacking the colony-specific hydrocarbons, the speed of returning foragers decreased significantly. The chemical environment of the nest mound contributes to the regulation of foraging behavior in harvester ants.

  View details for DOI 10.1007/s10886-011-9947-y

  View details for Web of Science ID 000291489500011

  View details for PubMedID 21494855

• Chemical Defense by the Native Winter Ant (Prenolepis imparis) against the Invasive Argentine Ant (Linepithema humile) PLOS ONE Sorrells, T. R., Kuritzky, L. Y., Kauhanen, P. G., Fitzgerald, K., Sturgis, S. J., Chen, J., Dijamco, C. A., Basurto, K. N., Gordon, D. M. 2011; 6 (4)

  Abstract

  The invasive Argentine ant (Linepithema humile) is established worldwide and displaces native ant species. In northern California, however, the native winter ant (Prenolepis imparis) persists in invaded areas. We found that in aggressive interactions between the two species, P. imparis employs a potent defensive secretion. Field observations were conducted at P. imparis nest sites both in the presence and absence of L. humile. These observations suggested and laboratory assays confirmed that P. imparis workers are more likely to secrete when outnumbered by L. humile. Workers of P. imparis were also more likely to secrete near their nest entrances than when foraging on trees. One-on-one laboratory trials showed that the P. imparis secretion is highly lethal to L. humile, causing 79% mortality. The nonpolar fraction of the secretion was chemically analyzed with gas chromatography/mass spectrometry, and found to be composed of long-chain and cyclic hydrocarbons. Chemical analysis of dissected P. imparis workers showed that the nonpolar fraction is derived from the Dufour's gland. Based on these conclusions, we hypothesize that this chemical defense may help P. imparis to resist displacement by L. humile.

  View details for DOI 10.1371/journal.pone.0018717

  View details for PubMedID 21526231

• Colony variation in the collective regulation of foraging by harvester ants BEHAVIORAL ECOLOGY Gordon, D. M., Guetz, A., Greene, M. J., Holmes, S. 2011; 22 (2): 429-435

  Abstract

  This study investigates variation in collective behavior in a natural population of colonies of the harvester ant, Pogonomyrmex barbatus. Harvester ant colonies regulate foraging activity to adjust to current food availability; the rate at which inactive foragers leave the nest on the next trip depends on the rate at which successful foragers return with food. This study investigates differences among colonies in foraging activity and how these differences are associated with variation among colonies in the regulation of foraging. Colonies differ in the baseline rate at which patrollers leave the nest, without stimulation from returning ants. This baseline rate predicts a colony's foraging activity, suggesting there is a colony-specific activity level that influences how quickly any ant leaves the nest. When a colony's foraging activity is high, the colony is more likely to regulate foraging. Moreover, colonies differ in the propensity to adjust the rate of outgoing foragers to the rate of forager return. Naturally occurring variation in the regulation of foraging may lead to variation in colony survival and reproductive success.

  View details for DOI 10.1093/beheco/arq218

  View details for Web of Science ID 000289299500033

  View details for PubMedCentralID PMC3071749

• Colony variation in the collective regulation of foraging by harvester ants. Behavioral ecology : official journal of the International Society for Behavioral Ecology Gordon, D. M., Guetz, A., Greene, M. J., Holmes, S. 2011; 22 (2): 429-435

  Abstract

  This study investigates variation in collective behavior in a natural population of colonies of the harvester ant, Pogonomyrmex barbatus. Harvester ant colonies regulate foraging activity to adjust to current food availability; the rate at which inactive foragers leave the nest on the next trip depends on the rate at which successful foragers return with food. This study investigates differences among colonies in foraging activity and how these differences are associated with variation among colonies in the regulation of foraging. Colonies differ in the baseline rate at which patrollers leave the nest, without stimulation from returning ants. This baseline rate predicts a colony's foraging activity, suggesting there is a colony-specific activity level that influences how quickly any ant leaves the nest. When a colony's foraging activity is high, the colony is more likely to regulate foraging. Moreover, colonies differ in the propensity to adjust the rate of outgoing foragers to the rate of forager return. Naturally occurring variation in the regulation of foraging may lead to variation in colony survival and reproductive success.

  View details for DOI 10.1093/beheco/arq218

  View details for PubMedID 22479133

  View details for PubMedCentralID PMC3071749

• The fusion of behavioral ecology and ecology BEHAVIORAL ECOLOGY Gordon, D. M. 2011; 22 (2): 225-230

  View details for DOI 10.1093/beheco/arq172

  View details for Web of Science ID 000289299500001

• Indirect benefits of symbiotic coccoids for an ant-defended myrmecophytic tree ECOLOGY Pringle, E. G., Dirzo, R., Gordon, D. M. 2011; 92 (1): 37-46

  Abstract

  The net benefits of mutualism depend directly on the costs and effectiveness of mutualistic services and indirectly on the interactions that affect those services. We examined interactions among Cordia alliodora myrmecophytic trees, their symbiotic ants Azteca pittieri, coccoid hemipterans, and foliar herbivores in two Neotropical dry forests. The tree makes two investments in symbiotic ants: it supplies nesting space, as domatia, and it provides phloem to coccoids, which then produce honeydew that is consumed by ants. Although higher densities of coccoids should have higher direct costs for trees, we asked whether higher densities of coccoids can also have higher indirect benefits for trees by increasing the effectiveness of ant defense against foliar herbivores. We found that trees benefited from ant defense against herbivores. Ants defended trees effectively only when colonies reached high densities within trees, and ant and coccoid densities within trees were strongly positively correlated. The benefits of reduced foliar herbivory by larger ant colonies were therefore indirectly controlled by the number of coccoids. Coccoid honeydew supply also affected per capita ant aggression against tree herbivores. Ants experimentally fed a carbohydrate-rich diet, analogous to sugar obtained from coccoids, were more aggressive against caterpillars per capita than ants fed a carbohydrate-poor diet. Ant defense was more effective on more valuable and vulnerable young leaves than on older leaves. Young domatia, associated with young leaves, contained higher coccoid densities than older domatia, which suggests that coccoids may also drive spatially favorable ant defense of the tree. If higher investments by one mutualistic partner are tied to higher benefits received from the other, there may be positive feedback between partners that will stabilize the mutualism. These results suggest that higher investment by trees in coccoids leads to more effective defense by ants against the tree's foliar herbivores.

  View details for Web of Science ID 000289552200006

  View details for PubMedID 21560674

• Adventures Among Ants: A Global Safari with a Cast of Trillions (Book Review) NATURE Book Review Authored by: Gordon, D. M. 2010; 465 (7295): 163-163

  View details for DOI 10.1038/465163a

  View details for Web of Science ID 000277558500017

• Fine-scale genetic structure and dispersal distance in the harvester ant Pogonomyrmex barbatus HEREDITY Suni, S. S., GORDON, D. M. 2010; 104 (2): 168-173

  Abstract

  Dispersal has important genetic and evolutionary consequences. It is notoriously difficult to study in some ant species, because reproductives fly from parent nests to mating aggregations and then to new nest sites. We used genetic techniques to measure dispersal distance and characterize patterns of genetic variation in a population of the harvester ant Pogonomyrmex barbatus. This population consists of two interdependent yet genetically distinct mitochondrial lineages, each associated with specific alleles at nuclear loci. We found moderate levels of genetic structure for both lineages and a significant pattern of isolation by distance when individual colonies were the operational unit of study. Dispersal distances calculated from the slope of the regression of genetic on geographic distance were 65.3 m for J1 and 85.8 m for J2. These results are consistent with previous observations of many mating aggregations over small geographic areas. In dependent-lineage populations like our study population, females must mate with males of the opposite lineage to produce workers, and with males of the same lineage to produce female reproductives. Because lineage ratios differ from 1:1 throughout the southwestern United States, restricted dispersal between sites with different lineage ratios could have important effects on dependent-lineage population dynamics. Our results suggest that it is unlikely that many individuals disperse from areas dominated by one lineage to areas dominated by another. Short dispersal distances lead to low gene flow, giving local populations evolutionary independence.

  View details for DOI 10.1038/hdy.2009.124

  View details for Web of Science ID 000273802800009

  View details for PubMedID 19773807

• The intertwined population biology of two Amazonian myrmecophytes and their symbiotic ants ECOLOGY Frederickson, M. E., Gordon, D. M. 2009; 90 (6): 1595-1607

  Abstract

  A major question in ecology is: how do mutualisms between species affect population dynamics? For four years, we monitored populations of two Amazonian myrmecophytes, Cordia nodosa and Duroia hirsuta, and their symbiotic ants. In this system, we investigated how positive feedback between mutualistic plants and ant colonies influenced population processes at two scales: (1) how modular organisms such as plants and ant colonies grew, or eta-demography, and (2) how populations grew, or N-demography. We found evidence of positive feedback between ant colony and plant growth rates. Plants with mutualistic ants (Azteca spp. and Myrmelachista schumanni) grew in a geometric or autocatalytic manner, such that the largest plants grew the most. By contrast, the growth of plants with parasitic ants (Allomerus octoarticulatus) saturated. Ant colonies occupied new domatia as fast as plants produced them, suggesting that mutualistic ant colonies also grew geometrically or autocatalytically to match plant growth. Plants became smaller when they lost ants. While unoccupied, plants continued to become smaller until they had lost all or nearly all their domatia. Hence, the loss of mutualistic ants limited plant growth. C. nodosa and D. hirsuta live longer than their ant symbionts and were sometimes recolonized after losing ants, which again promoted plant growth. Plant growth had fitness consequences for ants and plants; mortality and fecundity depended on plant size. Positive feedback between ants and plants allowed a few plants and ant colonies to become very large; these probably produced the majority of offspring in the next generation.

  View details for Web of Science ID 000266662500020

  View details for PubMedID 19569374

• How site fidelity leads to individual differences in the foraging activity of harvester ants BEHAVIORAL ECOLOGY Beverly, B. D., McLendon, H., Nacu, S., Holmes, S., Gordon, D. M. 2009; 20 (3): 633-638

  View details for DOI 10.1093/beheco/arp041

  View details for Web of Science ID 000265950200023

• Nest connectivity and colony structure in unicolonial Argentine ants INSECTES SOCIAUX Heller, N. E., Ingram, K. K., GORDON, D. M. 2008; 55 (4): 397-403

  View details for DOI 10.1007/s00040-008-1019-0

  View details for Web of Science ID 000261422700010

• Rainfall facilitates the spread, and time alters the impact, of the invasive Argentine ant OECOLOGIA Heller, N. E., Sanders, N. J., Shors, J. W., Gordon, D. M. 2008; 155 (2): 385-395

  Abstract

  Climate change may exacerbate invasions by making conditions more favorable to introduced species relative to native species. Here we used data obtained during a long-term biannual survey of the distribution of ant species in a 481-ha preserve in northern California to assess the influence of interannual variation in rainfall on the spread of invasive Argentine ants, Linepithema humile, and the displacement of native ant species. Since the survey began in 1993, Argentine ants have expanded their range into 74 new hectares. Many invaded hectares were later abandoned, so the range of Argentine ants increased in some years and decreased in others. Rainfall predicted both range expansion and interannual changes in the distribution of Argentine ants: high rainfall, particularly in summer months, promoted their spread in the summer. This suggests that an increase in rainfall will promote a wider distribution of Argentine ants and increase their spread into new areas in California. Surprisingly, the distribution of two native ant species also increased following high rainfall, but only in areas of the preserve that were invaded by L. humile. Rainfall did not have a negative impact on total native ant species richness in invaded areas. Instead, native ant species richness in invaded areas increased significantly over the 13 years of observation. This suggests that the impact of Argentine ants on naïve ant communities may be most severe early in the invasion process.

  View details for DOI 10.1007/s00442-007-0911-z

  View details for Web of Science ID 000253215900017

  View details for PubMedID 18004595

• The short-term regulation of foraging in harvester ants BEHAVIORAL ECOLOGY Gordon, D. M., Holmes, S., Nacu, S. 2008; 19 (1): 217-222

  View details for DOI 10.1093/beheco/arm125

  View details for Web of Science ID 000252305000029

• Male parentage in dependent-lineage populations of the harvester ant Pogonomyrmex barbatus MOLECULAR ECOLOGY Suni, S. S., Gignoux, C., Gordon, D. M. 2007; 16 (24): 5149-5155

  Abstract

  We investigated the extent to which workers reproduce in a dependent-lineage population of the monogynous harvester ant Pogonomyrmex barbatus. Dependent-lineage populations contain two interbreeding, yet genetically distinct mitochondrial lineages, each associated with specific alleles at nuclear loci. Workers develop from matings between lineages, and queens develop from matings within lineages, so queens must mate with males of both lineages to produce daughter queens and workers. Males develop from unfertilized eggs and are haploid. Worker production of males could lead to male-mediated gene flow between the lineages if worker-produced males were reproductively capable. This could result in the loss of the dependent-lineage system, because its persistence depends on the maintenance of allelic differences between the lineages. To investigate the extent of worker reproduction in P. barbatus, we genotyped 19-20 males and workers from seven colonies, at seven microsatellite loci, and 1239 additional males at two microsatellite loci. Our methods were powerful enough to detect worker reproduction if workers produced more than 0.39% of males in the population. We detected no worker-produced males; all males appeared to be produced by queens. Thus, worker reproduction is sufficiently infrequent to have little impact on the dependent-lineage system. These results are consistent with predictions based on inclusive fitness theory because the effective queen mating frequency calculated from worker genotypes was 4.26, which is sufficiently high for workers to police those that attempt to reproduce.

  View details for DOI 10.1111/j.1365-294X.2007.03492.x

  View details for Web of Science ID 000251671700005

  View details for PubMedID 18092991

• How patrollers set foraging direction in harvester ants AMERICAN NATURALIST Greene, M. J., Gordon, D. M. 2007; 170 (6): 943-948

  Abstract

  Recruitment to food or nest sites is well known in ants; the recruiting ants lay a chemical trail that other ants follow to the target site, or they walk with other ants to the target site. Here we report that a different process determines foraging direction in the harvester ant Pogonomyrmex barbatus. Each day, the colony chooses from among up to eight distinct foraging trails; colonies use different trails on different days. Here we show that the patrollers regulate the direction taken by foragers each day by depositing Dufour's secretions onto a sector of the nest mound about 20 cm long and leading to the beginning of a foraging trail. The patrollers do not recruit foragers all the way to food sources, which may be up to 20 m away. Fewer foragers traveled along a trail if patrollers had no access to the sector of the nest mound leading to that trail. Adding Dufour's gland extract to patroller-free sectors of the nest mound rescued foraging in that direction, while poison gland extract did not. We also found that in the absence of patrollers, most foragers used the direction they had used on the previous day. Thus, the colony's 30-50 patrollers act as gatekeepers for thousands of foragers and choose a foraging direction, but they do not recruit and lead foragers all the way to a food source.

  View details for DOI 10.1086/522843

  View details for Web of Science ID 000250832000016

  View details for PubMedID 18171176

• The devil to pay: a cost of mutualism with Myrmelachista schumanni ants in 'devil's gardens' is increased herbivory on Duroia hirsuta trees PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Frederickson, M. E., Gordon, D. M. 2007; 274 (1613): 1117-1123

  Abstract

  'Devil's gardens' are nearly pure stands of the myrmecophyte, Duroia hirsuta, that occur in Amazonian rainforests. Devil's gardens are created by Myrmelachista schumanni ants, which nest in D. hirsuta trees and kill other plants using formic acid as an herbicide. Here, we show that this ant-plant mutualism has an associated cost; by making devil's gardens, M. schumanni increases herbivory on D. hirsuta. We measured standing leaf herbivory on D. hirsuta trees and found that they sustain higher herbivory inside than outside devil's gardens. We also measured the rate of herbivory on nursery-grown D. hirsuta saplings planted inside and outside devil's gardens in ant-exclusion and control treatments. We found that when we excluded ants, herbivory on D. hirsuta was higher inside than outside devil's gardens. These results suggest that devil's gardens are a concentrated resource for herbivores. Myrmelachista schumanni workers defend D. hirsuta against herbivores, but do not fully counterbalance the high herbivore pressure in devil's gardens. We suggest that high herbivory may limit the spread of devil's gardens, possibly explaining why devil's gardens do not overrun Amazonian rainforests.

  View details for DOI 10.1098/rspb.2006.0415

  View details for Web of Science ID 000245472200015

  View details for PubMedID 17301016

  View details for PubMedCentralID PMC2124481

• Control without hierarchy NATURE Gordon, D. M. 2007; 446 (7132): 143-143

  View details for DOI 10.1038/446143a

  View details for Web of Science ID 000244718100025

  View details for PubMedID 17344838

• Structural complexity of chemical recognition cues affects the perception of group membership in the ants Linephithema humile and Aphaenogaster cockerelli JOURNAL OF EXPERIMENTAL BIOLOGY Greene, M. J., Gordon, D. M. 2007; 210 (5): 897-905

  Abstract

  Hydrocarbon profiles on the cuticle of social insects act as multi-component recognition cues used to identify membership in a species, a colony or, within colonies, cues about its reproductive status or task group. To examine the role of structural complexity in ant hydrocarbon recognition cues, we studied the species recognition response of two ant species, Linepithema humile and Aphaenogaster cockerelli, and the recognition of conspecifics by L. humile. The cuticular hydrocarbons of ants are composed of molecules of varying chain lengths from three structural classes, n-alkanes, methyl-branched alkanes and n-alkenes. We employed species recognition bioassays that measured the aggressive response of both species of ants to mixtures of hydrocarbon classes, single structural classes of hydrocarbons (n-alkanes, methyl-branched alkanes and n-alkenes), and controls. The results showed that a combination of at least two hydrocarbon structural classes was necessary to elicit an aggressive species recognition response. Moreover, no single class of hydrocarbons was more important than the others in eliciting a response. Similarly, in the recognition of conspecifics, Linepithema humile did not respond to a mixture of n-alkane cuticular hydrocarbons presented alone, but supplementation of nestmate hydrocarbon profiles with the n-alkanes did elicit high levels of aggression. Thus both L. humile and A. cockerelli required mixtures of hydrocarbons of different structural classes to recognize species and colony membership. It appears that information on species and colony membership is not in isolated components of the profile, but instead in the mixture of structural classes found in cuticular hydrocarbon profiles.

  View details for DOI 10.1242/jeb.02706

  View details for Web of Science ID 000244633000023

  View details for PubMedID 17297148

• Interaction rate informs harvester ant task decisions BEHAVIORAL ECOLOGY Greene, M. J., Gordon, D. M. 2007; 18 (2): 451-455

  View details for DOI 10.1093/beheco/arl105

  View details for Web of Science ID 000244658100025

• Seasonal spatial dynamics and causes of nest movement in colonies of the invasive Argentine ant (Linepithema humile) ECOLOGICAL ENTOMOLOGY Heller, N. E., Gordon, D. M. 2006; 31 (5): 499-510

  View details for DOI 10.1111/j.1365-2311.2006.00806.x

  View details for Web of Science ID 000240402600012

• Brood production and lineage discrimination in the red harvester ant (Pogonomyrmex barbatus) ECOLOGY Volny, V. P., Greene, M. J., Gordon, D. M. 2006; 87 (9): 2194-2200

  Abstract

  In contrast to the system of caste determination in most social insects, reproductive caste determination in some populations of Pogonomyrmex barbatus has a genetic basis. Populations that exhibit genetic caste determination are segregated into two distinct, genetic lineages. Same-lineage matings result in female reproductives, while inter-lineage matings result in workers. To investigate whether founding P. barbatus queens lay eggs of reproductive genotype, and to determine the fate of those eggs, we genotyped eggs, larvae, and pupae produced by naturally inseminated, laboratory-raised queens. We show that founding dependent lineage queens do lay eggs of reproductive genotype, and that the proportion of reproductive genotypes decreases over the course of development from eggs to larvae to pupae. Because queens must mate with a male of each lineage to produce both workers and female reproductives, it would benefit queens to be able to distinguish males of the two lineages. Here we show that P. barbatus males from the two genetic lineages differ in their cuticular hydrocarbon profiles. Queens could use male cuticular hydrocarbons as cues to assess the lineage of males at the mating aggregation, and possibly keep mating until they have mated with males of both lineages.

  View details for Web of Science ID 000240253000007

  View details for PubMedID 16995618

• Genetic caste determination in harvester ants: Possible origin and maintenance by cyto-nuclear epistasis ECOLOGY Linksvayer, T. A., Wade, M. J., Gordon, D. M. 2006; 87 (9): 2185-2193

  Abstract

  While reproductive caste in eusocial insects is usually determined by environmental factors, in some populations of the harvester ants, Pogonomyrmex barbatus and P. rugosus, caste has been shown to have a strong genetic component. This system of genetic caste determination (GCD) is characterized by between-caste nuclear variation and high levels of mitochondrial haplotype variation between alternative maternal lineages. Two previous genetic models, involving a single nuclear caste-determining locus or interactions between two nuclear loci, respectively, have been proposed to explain the GCD system. We propose a new model based on interactions between nuclear and mitochondrial genes that can better explain the co-maintenance of distinct nuclear and mitochondrial lineages. In our model, females with coevolved cyto-nuclear gene complexes, derived from intra-lineage mating, develop into gynes, while females with disrupted cyto-nuclear complexes, derived from inter-lineage mating, develop into workers. Both haplodiploidy and inbreeding facilitate the buildup of such coevolved cyto-nuclear complexes within lineages. In addition, the opportunity for both intra-lineage and inter-lineage mating in polyandrous populations facilitates the accumulation of gyne-biasing genes. This model may also help to explain the evolution of workerless social, parasites. We discuss similarities of GCD and cytoplasmic male sterility in plants and how worker production of males would affect the stability of GCD. Finally, we propose experiments and observations that might help resolve the origin and maintenance of this unusual system of caste determination.

  View details for Web of Science ID 000240253000006

  View details for PubMedID 16995617

• Forager activation and food availability in harvester ants ANIMAL BEHAVIOUR Schafer, R. J., Holmes, S., Gordon, D. M. 2006; 71: 815-822

  View details for DOI 10.1016/j.anbehav.2005.05.024

  View details for Web of Science ID 000236875200009

• Linking temporal and spatial scales in the study of an Argentine ant invasion BIOLOGICAL INVASIONS Heller, N. E., Sanders, N. J., GORDON, D. M. 2006; 8 (3): 501-507

  View details for DOI 10.1007/s10530-005-6411-3

  View details for Web of Science ID 000235306900009

• 'Devil's gardens' bedevilled by ants NATURE Frederickson, M. E., Greene, M. J., GORDON, D. M. 2005; 437 (7058): 495-496

  Abstract

  'Devil's gardens' are large stands of trees in the Amazonian rainforest that consist almost entirely of a single species, Duroia hirsuta, and, according to local legend, are cultivated by an evil forest spirit. Here we show that the ant Myrmelachista schumanni, which nests in D. hirsuta stems, creates devil's gardens by poisoning all plants except its host plants with formic acid. By killing these other plants, M. schumanni provides its colonies with abundant nest sites--a long-lasting benefit as colonies can live for 800 years.

  View details for DOI 10.1038/437495a

  View details for Web of Science ID 000232004800035

  View details for PubMedID 16177778

• Task-specific expression of the foraging gene in harvester ants MOLECULAR ECOLOGY Ingram, K. K., Oefner, P., GORDON, D. M. 2005; 14 (3): 813-818

  Abstract

  In social insects, groups of workers perform various tasks such as brood care and foraging. Transitions in workers from one task to another are important in the organization and ecological success of colonies. Regulation of genetic pathways can lead to plasticity in social insect task behaviour. The colony organization of advanced eusocial insects evolved independently in ants, bees, and wasps and it is not known whether the genetic mechanisms that influence behavioural plasticity are conserved across species. Here we show that a gene associated with foraging behaviour is conserved across social insect species, but the expression patterns of this gene are not. We cloned the red harvester ant (Pogonomyrmex barbatus) ortholog (Pbfor) to foraging, one of few genes implicated in social organization, and found that foraging behaviour in harvester ants is associated with the expression of this gene; young (callow) worker brains have significantly higher levels of Pbfor mRNA than foragers. Levels of Pbfor mRNA in other worker task groups vary among harvester ant colonies. However, foragers always have the lowest expression levels compared to other task groups. The association between foraging behaviour and the foraging gene is conserved across social insects but ants and bees have an inverse relationship between foraging expression and behaviour.

  View details for DOI 10.1111/j.1365-294X.2005.02450.x

  View details for Web of Science ID 000227132300013

  View details for PubMedID 15723672

• Variation in the transition from inside to outside work in the red harvester ant Pogonomyrmex barbatus INSECTES SOCIAUX Gordon, D. M., Chu, J., Lillie, A., Tissot, M., Pinter, N. 2005; 52 (3): 212-217

  View details for DOI 10.1007/s00040-004-0796-3

  View details for Web of Science ID 000231360400002

• The interactive effects of climate, life history, and interspecific neighbours on mortality in a population of seed harvester ants ECOLOGICAL ENTOMOLOGY Sanders, N. J., GORDON, D. M. 2004; 29 (5): 632-637

  View details for Web of Science ID 000223905200014

• Development of harvester ant colonies alters soil chemistry SOIL BIOLOGY & BIOCHEMISTRY Wagner, D., Jones, J. B., GORDON, D. M. 2004; 36 (5): 797-804

  View details for DOI 10.1016/j.soilbio.2004.01.009

  View details for Web of Science ID 000220840700007

• Cuticular hydrocarbons act as cues in the interaction network regulating harvester ant task allocation Annual Meeting of the Society-for-Integrative-and-Comparative-Biology Greene, M. J., GORDON, D. M. OXFORD UNIV PRESS INC. 2003: 846–46

  View details for Web of Science ID 000222235200176

• Genetic analysis of dispersal dynamics in an invading population of Argentine ants ECOLOGY Ingram, K. K., GORDON, D. M. 2003; 84 (11): 2832-2842

  View details for Web of Science ID 000187363200004

• Optimization, conflict, and nonoverlapping foraging ranges in ants AMERICAN NATURALIST Adler, F. R., GORDON, D. M. 2003; 162 (5): 529-543

  Abstract

  An organism's foraging range depends on the behavior of neighbors, the dynamics of resources, and the availability of information. We use a well-studied population of the red harvester ant Pogonomyrmex barbatus to develop and independently parameterize models that include these three factors. The models solve for an allocation of foraging ants in the area around the nest in response to other colonies. We compare formulations that optimize at the colony or individual level and those that do or do not include costs of conflict. Model predictions were compared with data collected on ant time budgets and ant density. The strategy that optimizes at the colony level but neglects costs of conflict predicts unrealistic levels of overlap. In contrast, the strategy that optimizes at the individual level predicts realistic foraging ranges with or without inclusion of conflict costs. Both the individual model and the colony model that includes conflict costs show good quantitative agreement with data. Thus, an optimal foraging response to a combination of exploitation and interference competition can largely explain how individual foraging behavior creates the foraging range of a colony. Deviations between model predictions and data indicate that colonies might allocate a larger than optimal number of foragers to areas near boundaries between foraging ranges.

  View details for Web of Science ID 000186719000001

  View details for PubMedID 14618533

• Social insects - Cuticular hydrocarbons inform task decisions NATURE Greene, M. J., GORDON, D. M. 2003; 423 (6935): 32-32

  View details for DOI 10.1038/423032a

  View details for Web of Science ID 000182561600031

  View details for PubMedID 12721617

• Resource-dependent interactions and the organization of desert ant communities ECOLOGY Sanders, N. J., GORDON, D. M. 2003; 84 (4): 1024-1031

  View details for Web of Science ID 000182813600022

• Community disassembly by an invasive species PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Sanders, N. J., Gotelli, N. J., Heller, N. E., GORDON, D. M. 2003; 100 (5): 2474-2477

  Abstract

  Invasive species pose serious threats to community structure and ecosystem function worldwide. The impacts of invasive species can be more pervasive than simple reduction of species numbers. By using 7 years of data in a biological preserve in northern California, we documented the disassembly of native ant communities during an invasion by the Argentine ant. In sites without the Argentine ant, native ant communities exhibit significant species segregation, consistent with competitive dynamics. In sites with the Argentine ant, native ant communities appear random or weakly aggregated in species co-occurrence. Comparisons of the same sites before and after invasion indicate that the shift from a structured to a random community is rapid and occurs within a year of invasion. Our results show that invasive species not only reduce biodiversity but rapidly disassemble communities and, as a result, alter community organization among the species that persist.

  View details for DOI 10.1073/pnas.0437913100

  View details for Web of Science ID 000181365000057

  View details for PubMedID 12604772

• The effects of proximity and colony age on interspecific interference competition between the desert ants Pogonomyrmex barbatus and Aphaenogaster cockerelli AMERICAN MIDLAND NATURALIST Barton, K. E., Sanders, N. J., Gordon, D. M. 2002; 148 (2): 376-382

  View details for Web of Science ID 000179014900016

• Characterization of polymorphic microsatellite loci in the red harvester ant, Pogonomyrmex barbatus MOLECULAR ECOLOGY NOTES Volny, V. P., GORDON, D. M. 2002; 2 (3): 302-303

  View details for DOI 10.1046/j.1471-8278.2002.00243.x

  View details for Web of Science ID 000177964300036

• The regulation of foraging activity in red harvester ant colonies AMERICAN NATURALIST Gordon, D. M. 2002; 159 (5): 509-518

  Abstract

  Behavioral plasticity in social insects is intriguing because colonies adjust to environmental change through the aggregated responses of individuals. Without central control, colonies adjust numbers of workers allocated to various tasks. Individual decisions are based on local information from the environment and other workers. This study examines how colonies of the seed-eating ant Pogonomyrmex barbatus adjust the intensity of foraging in an arid environment where conspecific neighbors compete for foraging area. The main question is how foragers decide whether to leave the nest. Patrollers search the area before foragers emerge. Removal experiments show that the return of the patrollers stimulates the onset of foraging, and later, the rate at which foragers return affects the rate at which foragers continue to leave the nest. Foraging activity is less sensitive to changes in the rate of returning foragers than to changes in the rate of returning patrollers. These results suggest that whether a colony forages at all on a given day depends on conditions detected early by patrollers but that once foraging begins, the intensity of foraging does not track, on an hourly timescale, how quickly foragers can find food.

  View details for Web of Science ID 000175302800007

  View details for PubMedID 18707433

• Genetic basis for queen-worker dimorphism in a social insect PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Volny, V. P., GORDON, D. M. 2002; 99 (9): 6108-6111

  Abstract

  Eusocial insects are characterized by reproductive division of labor, cooperative brood care, and the presence of a sterile worker caste. It is generally accepted that caste determination, including the differentiation of females into sterile workers and reproductive queens, is determined by environmental factors. In contrast, we find that in the red harvester ant, Pogonomyrmex barbatus, an individual's genotype at a particular microsatellite locus predicts its caste. We propose that this microsatellite locus is in tight linkage disequilibrium with at least one locus that plays an important role in caste determination. We call this the caste locus. We hypothesize that the system of caste determination we observe segregates the population into two distinct genetic lineages, each of which has distinct alleles at the microsatellite locus and also has distinct alleles, we propose, at caste. Workers are the offspring of parents from different lineages, and are thus heterozygous at caste, whereas queens are the offspring of parents from the same lineage, and are, therefore, homozygous at caste. This mode of caste determination has important consequences for the evolution of multiple mating by females and for control of the sex ratio and reproductive allocation in social insect colonies.

  View details for DOI 10.1073/pnas.092066699

  View details for Web of Science ID 000175377800066

  View details for PubMedID 11972049

  View details for PubMedCentralID PMC122910

• Resources and the flexible allocation of work in the desert ant, Aphaenogaster cockerelli INSECTES SOCIAUX Sanders, N. J., GORDON, D. M. 2002; 49 (4): 371-379

  View details for Web of Science ID 000179707700011

• Qualitative and quantitative differences in cuticular hydrocarbons between laboratory and field colonies of Pogonomyrmex barbatus COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY Tissot, M., Nelson, D. R., GORDON, D. M. 2001; 130 (3): 349-358

  Abstract

  Ants held in the laboratory and field ants of the species Pogonomyrmex barbatus have quantitative differences in their cuticular hydrocarbons and a qualitative difference in their methyl-branched hydrocarbons. Laboratory-held workers showed twice the hydrocarbon content as field ants. This difference was mainly due to higher amounts of straight-chain alkanes and methyl-branched alkanes in laboratory ants, whereas the proportion of the alkenes remained the same for both groups. In addition to the absence of some hydrocarbons in the field colonies, one of the methyl-branched hydrocarbons differed in amount and branching pattern between the two groups of ants. Whereas, notable peaks of 2-methylalkanes were identified in ants kept in the laboratory, these compounds could not be identified in ants living in their natural habitat. However, a trace amount of 4-methyltriacontane was found in lieu of the 2-methyltriacontane counterpart in field ants. Possible explanations for both qualitative and quantitative differences are discussed.

  View details for PubMedID 11567897

• Effect of weather on infestation of buildings by the invasive Argentine ant, Linepithema humile (Hymenoptera : Formicidae) AMERICAN MIDLAND NATURALIST Gordon, D. M., Moses, L., Falkovitz-Halpern, M., Wong, E. H. 2001; 146 (2): 321-328

  View details for Web of Science ID 000171342200009

• Task-related environment alters the cuticular hydrocarbon composition of harvester ants JOURNAL OF CHEMICAL ECOLOGY Wagner, D., Tissot, M., GORDON, D. 2001; 27 (9): 1805-1819

  Abstract

  Within a colony of harvester ants (Pogonomyrmex barbatus), workers in different task groups differ in the hydrocarbon composition of the cuticle. Foragers and patrollers, which spend extended periods of time outside the nest, have a higher proportion of saturated, unbranched hydrocarbons (n-alkanes) on the cuticle than nest maintenance workers, which spend only short periods of time outside the nest. We tested whether these task-related differences in ant cuticular chemistry arise from exposure to conditions outside the nest. Nest maintenance workers experiencing daily, short-term outside exposure developed a higher proportion of n-alkanes on the cuticle than workers kept inside the lab. Independent manipulations of ultraviolet radiation, relative humidity, and temperature revealed that only the combination of high temperature (ca. 38 degrees C) and low relative humidity (ca. 8%) increased the proportion of cuticular n-alkanes. The results indicate that warm dry conditions, such as those encountered when an ant leaves the nest, trigger changes in cuticular chemistry.

  View details for Web of Science ID 000170660400007

  View details for PubMedID 11545372

• Novel wax esters and hydrocarbons in the cuticular surface lipids of the red harvester ant, Pogonomyrmex barbatus COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY Nelson, D. R., Tissot, M., Nelson, L. J., Fatland, C. L., GORDON, D. M. 2001; 128 (3): 575-595

  Abstract

  The cuticular surface lipids of the red harvester ant, Pogonomyrmex barbatus, were found to contain minor amounts of novel wax esters, in addition to the major components, hydrocarbons. The wax esters ranged in carbon number from C19 to C31 and consisted of esters of both odd- and even-numbered alcohols and acids. Each wax ester with a given carbon number eluted at several different retention times indicating possible methyl branching in either the fatty acid or alcohol moiety, or in both moieties. Each eluting peak of wax esters consisted of a mixture of wax esters of the same carbon number in which the fatty acid moiety ranged from C8 to C18, and the alcohol moiety ranged from C8 to C17. Some wax esters were largely found on the head indicating they may be of a glandular origin. The hydrocarbons consisted of: n-alkanes, C23 to C33; odd-numbered n-alkenes, C27 to C35; and the major components, methyl-branched alkanes, C26 to over C49. Notable components of the methyl-branched alkanes were 2-methyltriacontane, and the novel trimethylalkanes with a single methylene between the first and second branch points, 13,15,19-trimethylhentriacontane and 13,15,21-trimethyltritriacontane.

  View details for Web of Science ID 000167569500021

  View details for PubMedID 11250553

• Long-term dynamics of the distribution of the invasive Argentine ant, Linepithema humile, and native ant taxa in northern California. Oecologia Sanders, N. J., Barton, K. E., Gordon, D. M. 2001; 127 (1): 123-130

  Abstract

  Invasive species, where successful, can devastate native communities. We studied the dynamics of the invasive Argentine ant, Linepithema humile, for 7 years in Jasper Ridge, a biological preserve in northern California. We monitored the distributions at the hectare scale of native ant taxa and L. humile in the spring and fall from 1993 to 1999. We also studied the invasion dynamics at a finer resolution by searching for ants in 1-m2 plots. Our results are similar at both scales. The distributions of several native species are not random with regard to L. humile; the distributions of several epigeic species with similar habitat affinities overlap much less frequently than expected with the distribution of L. humile. We found that season had a significant influence on the distributions of L. humile and several native taxa. Over the 7-year period, L. humile has increased its range size in Jasper Ridge largely at the expense of native taxa, but there is seasonal and yearly variation in this rate of increase. Studies of invasions in progress which sample across seasons and years may help to predict the spread and effects of invasive species.

  View details for DOI 10.1007/s004420000572

  View details for PubMedID 28547163

• Long-term dynamics of the distribution of the invasive Argentine ant, Linepithema humile, and native ant taxa in northern California OECOLOGIA Sanders, N. J., Barton, K. E., GORDON, D. M. 2001; 127 (1): 123-130

  View details for Web of Science ID 000167629200014

• A trade-off in task allocation between sensitivity to the environment and response time JOURNAL OF THEORETICAL BIOLOGY Pereira, H. M., GORDON, D. M. 2001; 208 (2): 165-184

  Abstract

  Task allocation is the process that adjusts the number of workers in each colony task in response to the environment. There is no central coordination of task allocation; instead workers use local cues from the environment and from other workers to decide which task to perform. We examine two aspects of task allocation: the sensitivity to the environment of task distribution, and the rate of response to environmental changes. We investigate how these two aspects are influenced by: (1) colony size, and (2) behavioral rules used by workers, i.e. how a worker uses cues from the environment and from social interactions with other workers in deciding which task to perform. We show that if workers use social cues in their choice of task, response time decreases with increasing colony size. Sensitivity of task distribution to the environment may decrease or not with colony size, depending on the behavioral rules used by workers. This produces a trade-off in task allocation: short response times can be achieved by increasing colony size, but at the cost of decreased sensitivity to the environment. We show that when a worker's response to social interactions depends on the local environment, sensitivity of task distribution to the environment is not affected by colony size and the trade-off is avoided.

  View details for Web of Science ID 000166507000005

  View details for PubMedID 11162062

• The effects of interspecific interactions on resource use and behavior in a desert ant OECOLOGIA Sanders, N. J., GORDON, D. M. 2000; 125 (3): 436-443

  View details for Web of Science ID 000165442700015

• The effects of interspecific interactions on resource use and behavior in a desert ant. Oecologia Sanders, N. J., Gordon, D. M. 2000; 125 (3): 436-443

  Abstract

  We examined how interspecific competition in ants affects resource use and behavior. To test how neighboring Myrmecocystus colonies influence the desert ant Aphaenogaster cockerelli, we placed temporary enclosures around Myrmecocystus spp. colonies and recorded the resources collected by A. cockerelli and the numbers of A. cockerelli ants engaged in various tasks outside the nest. When neighbors were enclosed, A. cockerelli colonies collected a significantly higher proportion of termites and significantly less plant matter than when neighbors were active. The numbers of A. cockerelli ants engaged in foraging behavior and nest maintenance work increased when Myrmecocystus colonies were enclosed. Interspecific interactions thus can affect the behavior and resource use of A. cockerelli colonies and may influence colony fitness.

  View details for DOI 10.1007/s004420000463

  View details for PubMedID 28547339

• Harvester ants utilize cuticular hydrocarbons in nestmate recognition JOURNAL OF CHEMICAL ECOLOGY Wagner, D., Tissot, M., Cuevas, W., GORDON, D. M. 2000; 26 (10): 2245-2257

  View details for Web of Science ID 000165665300001

• How resources and encounters affect the distribution of foraging activity in a seed-harvesting ant BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY Brown, M. J., GORDON, D. M. 2000; 47 (3): 195-203

  View details for Web of Science ID 000085378400011

• Colony age, neighborhood density and reproductive potential in harvester ants OECOLOGIA Wagner, D., GORDON, D. M. 1999; 119 (2): 175-182

  View details for Web of Science ID 000080321100004

• Colony age, neighborhood density and reproductive potential in harvester ants. Oecologia Wagner, D., Gordon, D. M. 1999; 119 (2): 175-182

  Abstract

  At about age 5 years, colonies of the harvester ant, Pogonomyrmex barbatus, begin to produce winged, sexual forms (alates) that mate in large annual aggregations. We examined how colony age and neighborhood density affect the numbers, body mass, and body fat of alates produced by 172 colonies ranging in age from 4 to 17 years. Over one-third (36%) of all colonies produced no alates. Failure to reproduce was independent of colony age. Of those colonies that did produce alates, older colonies produced more alates than younger colonies. Older colonies produced lighter female alates (in dry mass), but the total biomass of additional alates produced by older colonies far outweighed the reduced allocation to female alate body mass. Body fat content was much higher in female alates (36.0% on average) than in males (3.7% on average). Alate body fat content was not related to colony age. The fitness of female alates may be related to their fresh body mass; that of females captured after mating and reared in the laboratory was positively correlated with egg-laying rate, although not with the total number of eggs in the first brood. Neighborhood density was not related to alate number, mass, or fat content, in contrast to the results of a 1995 study at the site, in which alate numbers were negatively related to neighborhood density. Thus the influence of crowding on reproductive output appears to vary from year to year, perhaps in response to variation in rainfall and food supply. Alate output by individual colonies was correlated among years. These results suggest that a few, older colonies dominate the pool of reproductives year after year.

  View details for DOI 10.1007/s004420050774

  View details for PubMedID 28307966

• Encounter rate and task allocation in harvester ants BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY GORDON, D. M., Mehdiabadi, N. J. 1999; 45 (5): 370-377

  View details for Web of Science ID 000079984700007

• Behavioral interactions of the invasive Argentine ant with native ant species INSECTES SOCIAUX Human, K. G., Gordon, D. M. 1999; 46 (2): 159-163

  View details for Web of Science ID 000080856700009

• Task-related differences in the cuticular hydrocarbon composition of harvester ants, Pogonomyrmex barbatus JOURNAL OF CHEMICAL ECOLOGY Wagner, D., Brown, M. J., Broun, P., Cuevas, W., Moses, L. E., Chao, D. L., GORDON, D. M. 1998; 24 (12): 2021-2037

  View details for Web of Science ID 000077497300004

• Effects of abiotic factors on the distribution and activity of the invasive Argentine ant (Hymenoptera : Formicidae) ENVIRONMENTAL ENTOMOLOGY Human, K. G., Weiss, S., WEISS, A., Sandler, B., GORDON, D. M. 1998; 27 (4): 822-833

  View details for Web of Science ID 000075789800004

• The effect of neighbours on the mortality of harvester ant colonies JOURNAL OF ANIMAL ECOLOGY GORDON, D. M., Kulig, A. 1998; 67 (1): 141-148

  View details for Web of Science ID 000071538400012

• Effects of Argentine ants on invertebrate biodiversity in northern California CONSERVATION BIOLOGY Human, K. G., GORDON, D. M. 1997; 11 (5): 1242-1248

  View details for Web of Science ID A1997YB76000022

• Harvester ant nests, soil biota and soil chemistry. Oecologia Wagner, D., Brown, M. J., Gordon, D. M. 1997; 112 (2): 232-236

  Abstract

  Many ant species accumulate organic debris in the vicinity of their nests. These organic materials should provide a rich resource base for the soil biota. We examined the effect of harvester ant nests (Pogonomyrmex barbatus) on the soil community and soil chemistry. Ant nest soils supported 30-fold higher densities of microarthropods and 5-fold higher densities of protozoa than surrounding, control soils. The relative abundances of the major groups of protozoa differed as well: amoebae and ciliates were relatively overrepresented, and flagellates underrepresented, in ant nest versus control soils. Densities of bacteria and fungi were similar in the two soil types. Concentrations of nitrate, ammonium, phosphorus, and potassium were significantly higher in ant nest soils, while concentrations of magnesium, calcium, and water were similar in nest and control soils. Ant nest soils were marginally more acidic than controls. The results demonstrate that P. barbatus nests constitute a significant source of spatial heterogeneity in soil biota and soil chemistry in arid grasslands.

  View details for DOI 10.1007/s004420050305

  View details for PubMedID 28307575

• Effects of harvester ants on plant species distribution and abundance in a serpentine grassland OECOLOGIA Brown, M. J., Human, K. G. 1997; 112 (2): 237-243

  Abstract

  Seed harvesting ants can have important effects on the composition and structure of plant communities. We investigated two effects of Messor andrei, the black seed-harvesting ant, on a serpentine grassland plant community in northern California. First, to determine if selective seed predation by ants affects plant community composition, we excluded harvester ants from 1-mediameter circular plots of grassland. Abundances of all species on these plots and on control plots were measured before and after exclosure. Second, to determine if M. andrei nest mounds affect plant community composition, we compared plant species abundances on and off nest mounds. M. andrei deposit large amounts of organic matter on their nest mounds over a foraging season, so mounds may alter the edaphic environment. The exclusion of seed-harvesting activity did not cause changes in the plant community. Nest mounds had a strong effect on plant communities: there were many more grasses and fewer forbs on ant mounds, although at least one forb, Lepidium nitidum, produced twice as many seeds when it grew on nest mounds. We found that nest mounds formed islands of higher-temperature soil in the serpentine grassland.

  View details for Web of Science ID A1997YA69300014

  View details for PubMedID 28307576

• Harvester ant nests, soil biota and soil chemistry OECOLOGIA Wagner, D., Brown, M. J., GORDON, D. M. 1997; 112 (2): 232-236

  View details for Web of Science ID A1997YA69300013

• Networking ants NATURAL HISTORY GORDON, D. M. 1997; 106 (8): 26-26

  View details for Web of Science ID A1997XR37800005

• Individual specialisation and encounters between harvester ant colonies BEHAVIOUR Brown, M. J., GORDON, D. M. 1997; 134: 849-866

  View details for Web of Science ID A1997XY18700003

• The population consequences of territorial behavior TRENDS IN ECOLOGY & EVOLUTION GORDON, D. M. 1997; 12 (2): 63-66

  Abstract

  Many organisms compete for space, or for resource that are linked to space. Territorial behavior in animals is one expression of competition for space. Models of competition for space seek to predict how the arrangement of individuals in a population changes as new individuals appear, others die, and neighbors interact with each other; studies of territorial behaviour examine how neighbor interactions lead animals to establish and maintain their use of space. In recent work on compition for space and on territorial behaviour, there has been a shift from simple, general models to ones that incorporate heterogeneity in the spatial and temporal distribution of resources, and in the ways individuals use resources.

  View details for Web of Science ID A1997WF30400009

  View details for PubMedID 21237974

• Neighborhood density and reproductive potential in harvester ants. Oecologia Gordon, D. M., Wagner, D. 1997; 109 (4): 556-560

  Abstract

  When neighbors compete for resources, the characteristics of a neighborhood may affect fitness. We examined the relationship between reproductive success and the density and size/age characteristics of neighbors in a population of the seed-eating ant, Pogonomyrmex barbatus, in which the ages of all colonies were known. Reproductive success was estimated by trapping and counting the number of alate, reproductive ants emerging from the nest for the annual mating flight. Alate production was negatively related to neighborhood density. Decreased production of alates by more crowded colonies may be due to competition for food with surrounding colonies. Neighbor size/age was unrelated to alate production. If alate production is correlated with lifetime reproductive success, these results suggest that selection favors colonies that monopolize more space, whatever the size of neighboring colonies.

  View details for DOI 10.1007/s004420050116

  View details for PubMedID 28307339

• Neighborhood density and reproductive potential in harvester ants OECOLOGIA GORDON, D. M., Wagner, D. 1997; 109 (4): 556-560

  View details for Web of Science ID A1997WM37800009

• Founding, foraging, and fighting: Colony size and the spatial distribution of harvester ant nests ECOLOGY GORDON, D. M., Kulig, A. W. 1996; 77 (8): 2393-2409

  View details for Web of Science ID A1996VY49700012

• The organization of work in social insect colonies NATURE GORDON, D. M. 1996; 380 (6570): 121-124

  View details for Web of Science ID A1996TZ97800039

• Effects of social group size on information transfer and task allocation EVOLUTIONARY ECOLOGY Pacala, S. W., GORDON, D. M., Godfray, H. C. 1996; 10 (2): 127-165

  View details for Web of Science ID A1996UB42700001

• Exploitation and interference competition between the invasive Argentine ant, Linepithema humile, and native ant species OECOLOGIA Human, K. G., GORDON, D. M. 1996; 105 (3): 405-412

  View details for Web of Science ID A1996TV85000016

• Exploitation and interference competition between the invasive Argentine ant, Linepithema humile, and native ant species. Oecologia Human, K. G., Gordon, D. M. 1996; 105 (3): 405-412

  Abstract

  Interactions between the invasive Argentine ant, Linepithema humile, and native ant species were studied in a 450-ha biological reserve in northern California. Along the edges of the invasion, the presence of Argentine ants significantly reduced the foraging success of native ant species, and vice versa. Argentine ants were consistently better than native ants at exploiting food sources: Argentine ants found and recruited to bait more consistently and in higher numbers than native ant species, and they foraged for longer periods throughout the day. Native ants and Argentine ants frequently fought when they recruited to the same bait, and native ant species were displaced from bait during 60% of these encounters. In introduction experiments, Argentine ants interfered with the foraging of native ant species, and prevented the establishment of new colonies of native ant species by preying upon winged native ant queens. The Argentine ants' range within the preserve expanded by 12 ha between May 1993 and May 1994, and 13 between September 1993 and September 1994, with a corresponding reduction of the range of native ant species. Although some native ants persist locally at the edges of the invasion of Argentine ants, most eventually disappear from invaded areas. Both interference and exploitation competition appear to be important in the displacement of native ant species from areas invaded by Argentine ants.

  View details for DOI 10.1007/BF00328744

  View details for PubMedID 28307114

• THE EXPANDABLE NETWORK OF ANT EXPLORATION ANIMAL BEHAVIOUR GORDON, D. M. 1995; 50: 995-1007

  View details for Web of Science ID A1995TA68700011

• THE DEVELOPMENT OF AN ANT COLONY FORAGING RANGE ANIMAL BEHAVIOUR GORDON, D. M. 1995; 49 (3): 649-659

  View details for Web of Science ID A1995QM72800009

• THE DEVELOPMENT OF ORGANIZATION IN AN ANT COLONY AMERICAN SCIENTIST GORDON, D. M. 1995; 83 (1): 50-57

  View details for Web of Science ID A1995QL57200017

• THE SPATIAL SCALE OF SEED COLLECTION BY HARVESTER ANTS OECOLOGIA GORDON, D. M. 1993; 95 (4): 479-487

  View details for Web of Science ID A1993MB23600005

• The spatial scale of seed collection by harvester ants. Oecologia Gordon, D. M. 1993; 95 (4): 479-487

  Abstract

  Colonies of the seed-eating ant, Pogonomyrmex barbatus, compete with neighboring colonies for foraging areas. In a conflict over foraging area, what is at stake? This depends on how resources are distributed in time and space: if certain regions consistently provide particularly nutritious seed species, or especially abundant seeds, such regions will be of greater value to a colony. During the summer, seeds were taken from returning foragers in colonies located in 4 different vegetation types. There was no relation between the vegetation currently growing in the foraging area, and the species of seeds collected by ants. During the summer, ants collect mostly seeds produced in previous seasons and dispersed by wind and flooding. In 1991, colonies in all vegetation types collected mostly Bouteloua aristidoides; in 1992, Eriastrum diffusum and Plantago patagonica. There was no relation between colony density and numbers of seeds collected. Seed species collected by ants were compared in different colonies, and on different foraging trails within a colony. The results show that seed patches are distributed on the scale of distances between nests, not the smaller scale of different foraging trails of one colony. It appears that colonies are competing for any space in which to search for seeds, not competing for certain regions of consistently high value.

  View details for DOI 10.1007/BF00317431

  View details for PubMedID 28313287

• WHAT IS THE FUNCTION OF ENCOUNTER PATTERNS IN ANT COLONIES ANIMAL BEHAVIOUR GORDON, D. M., Paul, R. E., Thorpe, K. 1993; 45 (6): 1083-1100

  View details for Web of Science ID A1993LH44900004

• HOW COLONY GROWTH AFFECTS FORAGER INTRUSION BETWEEN NEIGHBORING HARVESTER ANT COLONIES BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY GORDON, D. M. 1992; 31 (6): 417-427

  View details for Web of Science ID A1992KC33800006

• INFORMATION COLLECTION AND SPREAD BY NETWORKS OF PATROLLING ANTS AMERICAN NATURALIST Adler, F. R., GORDON, D. M. 1992; 140 (3): 373-400

  Abstract

  To study how a social group, such as an ant colony, monitors events occurring throughout its territory, we present a model of a network of patrolling ants engaged in information collection and dissemination. In this network, individuals follow independent paths through a region and can exchange signals with each other upon encounter. The paths of the ants are described by correlated random walks. Through simulations and analytic approximations, including a new approach to the spatial logistic equation, we study the efficiency with which such a network discovers a constantly changing stream of "events" scattered throughout the region and the speed with which information spreads to all ants in the network. We demonstrate that efficiency of event discovery and the speed of information spread are enhanced by increased network size and straighter individual ant paths, and that these two effects interact. The results lead to predictions regarding the relations among species-specific movement patterns, colony size, and ant ecology.

  View details for Web of Science ID A1992JG85800002

  View details for PubMedID 19426049

• THE ALLOCATION OF FORAGERS IN RED WOOD ANTS ECOLOGICAL ENTOMOLOGY GORDON, D. M., Rosengren, R., Sundstrom, L. 1992; 17 (2): 114-120

  View details for Web of Science ID A1992HX04900004

• WITTGENSTEIN AND ANT-WATCHING BIOLOGY & PHILOSOPHY GORDON, D. M. 1992; 7 (1): 13-25

  View details for Web of Science ID A1992HD96700002

• VARIATION AND CHANGE IN BEHAVIORAL ECOLOGY ECOLOGY GORDON, D. M. 1991; 72 (4): 1196-1203

  View details for Web of Science ID A1991GB18500004

• BEHAVIORAL FLEXIBILITY AND THE FORAGING ECOLOGY OF SEED-EATING ANTS AMERICAN NATURALIST GORDON, D. M. 1991; 138 (2): 379-411

  View details for Web of Science ID A1991GJ83500006