Callie Chappell is a Ph.D. candidate in Ecology and Evolution with the Fukami Lab. Callie is an ecologist and studies how genetic variation influences how ecological communities change over time. Her dissertation research focuses on nectar-inhabiting yeast and bacteria. With a background in bioengineering, Callie is particularly interested in the conservation and policy impacts of gene editing wild organisms and the cascading impacts that genetic variation can have on ecological and evolutionary processes.

Outside of the lab, Callie leads several groups that work in the intersection of science and society. Callie was the 2020-21 President of Stanford Science Policy Group (SSPG), a chapter of the National Science Policy Network and student organization that engages scientists with policy on the local, state, national, and international level. Callie also co-leads BioJam, an education program that collaborates with high school students and community organizations from low- income communities in the Greater Bay Area of California. BioJam participants and organizers learn together about bioengineering and biodesign through the lens of culture and creativity. Callie is also a professional artist and scientific illustrator. Callie has participated in several fellowships at the intersection of science and society including the Mirzayan Science and Technology Policy with the National Academies of Sciences, Engineering, and Medicine (2021), Graduate Ethics Fellow with Stanford’s McCoy Center for Ethics in Society (2019-2020), BioFutures Fellow with the Stanford Bio Policy and Leadership in Society (Bio.Polis) Initiative (2020-2021), and Katherine S. McCarter Policy Fellow with the Ecological Society of America (2020).

Honors & Awards

  • Graduate Research Fellowship (GRFP), National Science Foundation (2017)
  • Hubert Shaw and Sandra Lui Graduate Fellowship (SGF), Stanford University (2017)
  • Excellence in Teaching Award, Department of Biology, Stanford (2019)
  • Frances Lou Kallman Award, Department of Biology, Stanford (2020)

Boards, Advisory Committees, Professional Organizations

  • Graduate Council Chair (2020), American Society of Naturalists (2019 - Present)
  • Member, American Society of Microbiology (2018 - Present)
  • Member, Ecological Society of America (2018 - Present)

Professional Education

  • Doctor of Philosophy, Stanford University, BIO-PHD (2023)
  • B.S., University of Michigan, Biology (2016)
  • M.Sc., University of Michigan, Molecular, Cellular, & Developmental Biology (2017)

Stanford Advisors

All Publications

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


    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


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


    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