Christopher Knight

All Publications

• Conspecific cues, not starvation, mediate barren urchin response to predation risk. Oecologia Knight, C. J., Dunn, R. P., Long, J. D. 2022

  Abstract

  Prey state and prey density mediate antipredator responses that can shift community structure and alter ecosystem processes. For example, well-nourished prey at low densities (i.e., prey with higher per capita predation risk) should respond strongly to predators. Although prey state and density often co-vary across habitats, it is unclear if prey responses to predator cues are habitat-specific. We used mesocosms to compare the habitat-specific responses of purple sea urchins (Strongylocentrotus purpuratus) to waterborne cues from predatory lobsters (Panulirus interruptus). We predicted that urchins from kelp forests (i.e., in well-nourished condition) tested at low densities typically observed in this habitat would respond more strongly to predation risk than barren urchins (i.e., in less nourished condition) tested at high densities typically observed in this habitat. Indeed, when tested at densities associated with respective habitats, urchins from forests, but not barrens, reduced kelp grazing by 69% when exposed to lobster risk cues. Barren urchins that were unresponsive to predator cues at natural, high densities suddenly responded strongly to lobster cues when conspecific densities were reduced. Strong responses of low densities of barren urchins persisted across feeding history (i.e. 0-64days of starvation). This suggests that barren urchins can respond to predators but typically do not because of high conspecific densities. Because high densities of urchins in barrens should weaken the non-consumptive effects of lobsters, urchins in these habitats may continue to graze in the presence of predators thereby providing a feedback that maintains urchin barrens.

  View details for DOI 10.1007/s00442-022-05225-5

  View details for PubMedID 35907124

• Promoting equity in scientific recommendations for high seas governance One Earth Chapman, M. S., Oestreich, W. K., Frawley, T. H., Boettiger, C., Diver, S., Santos, B. S., Scoville, C., Armstrong, K., Blondin, H., Chand, K., Haulsee, D. E., Knight, C. J., Crowder, L. B. 2021; 4 (6): 790-794

  View details for DOI 10.1016/j.oneear.2021.05.011

• 3D genomics across the tree of life reveals condensin II as a determinant of architecture type. Science (New York, N.Y.) Hoencamp, C., Dudchenko, O., Elbatsh, A. M., Brahmachari, S., Raaijmakers, J. A., van Schaik, T., Sedeño Cacciatore, Á., Contessoto, V. G., van Heesbeen, R. G., van den Broek, B., Mhaskar, A. N., Teunissen, H., St Hilaire, B. G., Weisz, D., Omer, A. D., Pham, M., Colaric, Z., Yang, Z., Rao, S. S., Mitra, N., Lui, C., Yao, W., Khan, R., Moroz, L. L., Kohn, A., St Leger, J., Mena, A., Holcroft, K., Gambetta, M. C., Lim, F., Farley, E., Stein, N., Haddad, A., Chauss, D., Mutlu, A. S., Wang, M. C., Young, N. D., Hildebrandt, E., Cheng, H. H., Knight, C. J., Burnham, T. L., Hovel, K. A., Beel, A. J., Mattei, P. J., Kornberg, R. D., Warren, W. C., Cary, G., Gómez-Skarmeta, J. L., Hinman, V., Lindblad-Toh, K., Di Palma, F., Maeshima, K., Multani, A. S., Pathak, S., Nel-Themaat, L., Behringer, R. R., Kaur, P., Medema, R. H., van Steensel, B., de Wit, E., Onuchic, J. N., Di Pierro, M., Lieberman Aiden, E., Rowland, B. D. 2021; 372 (6545): 984-989

  Abstract

  We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes.

  View details for DOI 10.1126/science.abe2218

  View details for PubMedID 34045355

• COVID-19 reveals vulnerability of small-scale fisheries to global market systems. The Lancet. Planetary health Knight, C. J., Burnham, T. L., Mansfield, E. J., Crowder, L. B., Micheli, F. n. 2020; 4 (6): e219

  View details for DOI 10.1016/S2542-5196(20)30128-5

  View details for PubMedID 32559437

• Predation on competing mussel species: Patterns of prey consumption and its potential role in species coexistence JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY Escobar, J. B., Knight, C., Navarrete, S. A. 2018; 504: 38–46

  View details for DOI 10.1016/j.jembe.2018.03.008

  View details for Web of Science ID 000432770300005

• Complex Consequences of Herbivory and Interplant Cues in Three Annual Plants PLOS ONE Pearse, I. S., Porensky, L. M., Yang, L. H., Stanton, M. L., Karban, R., Bhattacharyya, L., Cox, R., Dove, K., Higgins, A., Kamoroff, C., Kirk, T., Knight, C., Koch, R., Parker, C., Rollins, H., Tanner, K. 2012; 7 (5): e38105

  Abstract

  Information exchange (or signaling) between plants following herbivore damage has recently been shown to affect plant responses to herbivory in relatively simple natural systems. In a large, manipulative field study using three annual plant species (Achyrachaena mollis, Lupinus nanus, and Sinapis arvensis), we tested whether experimental damage to a neighboring conspecific affected a plant's lifetime fitness and interactions with herbivores. By manipulating relatedness between plants, we assessed whether genetic relatedness of neighboring individuals influenced the outcome of having a damaged neighbor. Additionally, in laboratory feeding assays, we assessed whether damage to a neighboring plant specifically affected palatability to a generalist herbivore and, for S. arvensis, a specialist herbivore. Our study suggested a high level of contingency in the outcomes of plant signaling. For example, in the field, damaging a neighbor resulted in greater herbivory to A. mollis, but only when the damaged neighbor was a close relative. Similarly, in laboratory trials, the palatability of S. arvensis to a generalist herbivore increased after the plant was exposed to a damaged neighbor, while palatability to a specialist herbivore decreased. Across all species, damage to a neighbor resulted in decreased lifetime fitness, but only if neighbors were closely related. These results suggest that the outcomes of plant signaling within multi-species neighborhoods may be far more context-specific than has been previously shown. In particular, our study shows that herbivore interactions and signaling between plants are contingent on the genetic relationship between neighboring plants. Many factors affect the outcomes of plant signaling, and studies that clarify these factors will be necessary in order to assess the role of plant information exchange about herbivory in natural systems.

  View details for DOI 10.1371/journal.pone.0038105

  View details for Web of Science ID 000305338500088

  View details for PubMedID 22675439

  View details for PubMedCentralID PMC3364994