Callie Chappell

All Publications

• Protect transgender scientists. Science (New York, N.Y.) Sinnott-Armstrong, N., Forsythe, D., Benoit, J. M., Chappell, C. R., Coe, L. S., de Oliveira, B. F., Evans, N., Fagre, A. C., Gilligan, J. M., Hamilton, M., Henneberry, C. M., Ishaq, S. L., Johnston, J., Krichilsky, E., Lopez, J. A., McMonigal, K., Ortiz Alvarez de la Campa, M., Rahman, R., Schwartz, N. E., Talluto, L., Taylor, E. J., Vargas-Muñiz, J. M., Weissman, J. L. 2025; 388 (6753): 1283-1284

  View details for DOI 10.1126/science.ady0962

  View details for PubMedID 40536977

• Building an inclusive culture at scientific meetings: foundations for future progress. Microbiology (Reading, England) Maringer, K., Cunningham-Oakes, E., Lane, F., Jones, K. L., Rodrigues de Oliveira, B. F., Baba-Dikwa, A., Mitra, A., Perez-Sepulveda, B., Chappell, C. R., Macori, G., Donovan-Banfield, I., Vohra, P., Casey, R., Nepal, R., Khan, C. M. 2025; 171 (2)

  Abstract

  Scientific meetings and conferences are crucial in knowledge dissemination, fostering collaborations, professional development and inspiring innovative research. However, their traditional structure and organization have remained largely unchanged, perpetuating barriers that continue to exclude scientists from historically marginalized backgrounds. In response, the Microbiology Society has begun its journey to address these longstanding challenges, redesigning its meetings to create a more inclusive culture and a welcoming environment for all participants.

  View details for DOI 10.1099/mic.0.001527

  View details for PubMedID 39912341

• Queer- and trans-inclusive faculty hiring-A call for change. PLoS biology Weissman, J. L., Chappell, C. R., Francesco Rodrigues de Oliveira, B., Evans, N., Fagre, A. C., Forsythe, D., Frese, S. A., Gregor, R., Ishaq, S. L., Johnston, J., K R, B., Matsuda, S. B., McCarren, S., Ortiz Alvarez de la Campa, M., Roepke, T. A., Sinnott-Armstrong, N., Stobie, C. S., Talluto, L., Vargas-Muñiz, J. M. 2024; 22 (11): e3002919

  Abstract

  As queer and trans scientists, we face varied and systemic barriers to our professional success, resulting in our relative absence from faculty ranks at many institutions. In this Perspective, we call for a change in faculty hiring practices and present concrete guidance to make it a more inclusive process.

  View details for DOI 10.1371/journal.pbio.3002919

  View details for PubMedID 39576815

• Transcriptional Responses to Priority Effects in Nectar Yeast. Molecular ecology Chappell, C. R., Goddard, P. C., Golden, L. A., Hernandez, J., Ortiz Chavez, D., Hossine, M., Herrera Paredes, S., VanValkenburg, E., Nell, L. A., Fukami, T., Dhami, M. K. 2024: e17553

  Abstract

  Priority effects, where the order and timing of species arrival influence the assembly of ecological communities, have been observed in a variety of taxa and habitats. However, the genetic and molecular basis of priority effects remains unclear, hindering a better understanding of when priority effects will be strong. We sought to gain such an understanding for the nectar yeast Metschnikowia reukaufii commonly found in the nectar of our study plant, the hummingbird-pollinated Diplacus (Mimulus) aurantiacus. In this plant, M. reukaufii can experience strong priority effects when it reaches flowers after other nectar yeasts, such as M. rancensis. After inoculation into two contrasting types of synthetic nectar simulating early arrival of M. rancensis, we conducted whole-transcriptome sequencing of 108 strains of M. reukaufii. We found that several genes were differentially expressed in M. reukaufii strains when the nectar had been conditioned by growth of M. rancensis. Many of these genes were associated with amino acid metabolism, suggesting that M. reukaufii strains responded molecularly to the reduction in amino acid availability caused by M. rancensis. Furthermore, investigation of expression quantitative trait loci (eQTLs) revealed that genes involved in amino acid transport and resistance to antifungal compounds were enriched in some genetic variants of M. reukaufii. We also found that gene expression was associated with population growth rate, particularly when amino acids were limited. These results suggest that intraspecific genetic variation in the ability of nectar yeasts to respond to nutrient limitation and direct fungal competition underpins priority effects in this microbial system.

  View details for DOI 10.1111/mec.17553

  View details for PubMedID 39450887

• Building a queer- and trans-inclusive microbiology conference. mSystems Gregor, R., Johnston, J., Coe, L. S., Evans, N., Forsythe, D., Jones, R., Muratore, D., de Oliveira, B. F., Szabo, R., Wan, Y., Williams, J., Chappell, C. R., Matsuda, S. B., Ortiz Alvarez de la Campa, M., Queer and Trans in Microbiology Consortium, Weissman, J. L., Fagre, A. C., Frese, S. A., Hamilton, M., Labbate, M., Mollner, M., Moroenyane, I., Pacciani-Mori, L., Piedade, G. J., Pontrelli, S., Yang, M. Y., Weiss, A. C., Zablocki, O., Vyas, H. K. 2023: e0043323

  Abstract

  Microbiology conferences can be powerful places to build collaborations and exchange ideas, but for queer and transgender (trans) scientists, they can also become sources of alienation and isolation. Many conference organizers would like to create welcoming and inclusive events but feel ill-equipped to make this vision a reality, and a historical lack of representation of queer and trans folks in microbiology means we rarely occupy these key leadership roles ourselves. Looking more broadly, queer and trans scientists are systematically marginalized across scientific fields, leading to disparities in career outcomes, professional networks, and opportunities, as well as the loss of unique scientific perspectives at all levels. For queer and trans folks with multiple, intersecting, marginalized identities, these barriers often become even more severe. Here, we draw from our experiences as early-career microbiologists to provide concrete, practical advice to help conference organizers across research communities design inclusive, safe, and welcoming conferences, where queer and trans scientists can flourish.

  View details for DOI 10.1128/msystems.00433-23

  View details for PubMedID 37800938

• Fostering science-art collaborations: A toolbox of resources. PLoS biology Chappell, C. R., Muglia, L. J. 2023; 21 (2): e3001992

  Abstract

  Scientists and artists are both motivated by creativity and curiosity, and science and art can be mutually reinforcing, supporting discovery and innovation. This Community Page highlights resources for individuals, groups, and institutions to advance science-art collaborations.

  View details for DOI 10.1371/journal.pbio.3001992

  View details for PubMedID 36757944

• Wide-ranging consequences of priority effects governed by an overarching factor. eLife Chappell, C. R., Dhami, M. K., Bitter, M. C., Czech, L., Herrera Paredes, S., Barrie, F. B., Calderon, Y., Eritano, K., Golden, L., Hekmat-Scafe, D., Hsu, V., Kieschnick, C., Malladi, S., Rush, N., Fukami, T. 2022; 11

  Abstract

  Priority effects, where arrival order and initial relative abundance modulate local species interactions, can exert taxonomic, functional, and evolutionary influences on ecological communities by driving them to alternative states. It remains unclear if these wide-ranging consequences of priority effects can be explained systematically by a common underlying factor. Here, we identify such a factor in an empirical system. In a series of field and laboratory studies, we focus on how pH affects nectar-colonizing microbes and their interactions with plants and pollinators. In a field survey, we found that nectar microbial communities in a hummingbird-pollinated shrub, Diplacus (formerly Mimulus) aurantiacus, exhibited abundance patterns indicative of alternative stable states that emerge through domination by either bacteria or yeasts within individual flowers. In addition, nectar pH varied among D. aurantiacus flowers in a manner that is consistent with the existence of these alternative stable states. In laboratory experiments, Acinetobacter nectaris, the bacterium most commonly found in D. aurantiacus nectar, exerted a strongly negative priority effect against Metschnikowia reukaufii, the most common nectar-specialist yeast, by reducing nectar pH. This priority effect likely explains the mutually exclusive pattern of dominance found in the field survey. Furthermore, experimental evolution simulating hummingbird-assisted dispersal between flowers revealed that M. reukaufii could evolve rapidly to improve resistance against the priority effect if constantly exposed to A. nectaris-induced pH reduction. Finally, in a field experiment, we found that low nectar pH could reduce nectar consumption by hummingbirds, suggesting functional consequences of the pH-driven priority effect for plant reproduction. Taken together, these results show that it is possible to identify an overarching factor that governs the eco-evolutionary dynamics of priority effects across multiple levels of biological organization.

  View details for DOI 10.7554/eLife.79647

  View details for PubMedID 36300797

• Bioengineering Everywhere, for Everyone ISSUES IN SCIENCE AND TECHNOLOGY Chappell, C. R., Perez, R., Takara, C. 2022; 38 (3): 88-90

  View details for Web of Science ID 000856017200021

• Nectar yeasts: a natural microcosm for ecology. Yeast (Chichester, England) Chappell, C. R., Fukami, T. 2018; 35 (6): 417–23

  Abstract

  The species of yeasts that colonize floral nectar can modify the mutualistic relationships between plants and pollinators by changing the chemical properties of nectar. Recent evidence supporting this possibility has led to increased interest among ecologists in studying these fungi as well as the bacteria that interact with them in nectar. Although not fully explored, nectar yeasts also constitute a promising natural microcosm that can be used to facilitate development of general ecological theory. We discuss the methodological and conceptual advantages of using nectar yeasts from this perspective, including simplicity of communities, tractability of dispersal, replicability of community assembly, and the ease with which the mechanisms of species interactions can be studied in complementary experiments conducted in the field and the laboratory. To illustrate the power of nectar yeasts as a study system, we discuss several topics in community ecology, including environmental filtering, priority effects, and metacommunity dynamics. An exciting new direction is to integrate metagenomics and comparative genomics into nectar yeast research to address these fundamental ecological topics.

  View details for PubMedID 29476620

• Nectar yeasts: a natural microcosm for ecology YEAST Chappell, C. R., Fukami, T. 2018; 35 (6): 417–23

  View details for DOI 10.1002/yea.3311

  View details for Web of Science ID 000434281100002