University Distinguished Professor, Dept. Ecology & Evolutionary Biology University of Arizona

Editor in Chief, The American Naturalist

Ph.D., M.Sc., Ecology & Evolutionary Biology, University of Michigan

A.B. Brown University

Using a combination of field observations and experiments, I investigate how population processes, abiotic conditions and community context determine net effects of the interactions for the fitness of each participant species.  Specific conceptual areas of interest include: (1) conflicts of interest between mutualists and their consequences for the maintenance of beneficial outcomes in these interactions and (2) context-dependent outcomes in both mutualisms and antagonisms. I am also collaborating on theoretical and empirical investigation of (i) the fragility of mutualisms in light of conservation threats and mechanisms of restoring disrupted interactions and (ii) the causes and consequences of “cheating” within mutualism.

Click here for a film highlighting Judie’s work.

Paul J. CaraDonna

Ph.D. Candidate Botany, Humboldt State University

As a biologist I am interested in how the timing of important life history events (phenology) and local community context influence the outcome of ecological interactions. My work places an emphasis on the phenology of plant-pollinator interactions within the context of abiotic change. I do this work at the University of Arizona and The Rocky Mountain Biological Laboratory (RMBL) in Colorado. My ongoing research projects include: (1) drivers of plant and pollinator phenology, (2) investigation of the mechanisms and consequences of altered phenology for bee-flower interactions, (3) nesting biology and pollen diet of wild bees, and (4) examination of the consequences of mistimed interactions between the Broad-tailed Hummingbird and its floral resources along its migration route.  Much of this work aims to move beyond the plant-pollinator phenological mismatch hypothesis by exploring the effects of climate change through the lens of community-scale interactions.

Ginny Fitzpatrick

Ph.D. Candidate Ecology & Evolutionary Biology, University of Arizona

As a Ph.D. student I am interested in the thermal ecology of mutualism.  Mutualism is often a complex interaction among multiple species, each of which may respond to temperature differently. Specifically, I investigate the consequences of temperature for the ant-plant interaction between Ferocactus wislizeni and its common ant defenders at the Desert Research Laboratory in Tucson.  The barrel cactus exudes nectar from extrafloral glands, attracting ants which protect the plants against herbivores.  The level of protection that the mutualist ant species provide to cacti varies greatly.  My dissertation research explores how these mutualistic partners and the interactions among them respond to temperature.  Very little is known about the thermal ecology of species interactions and further research is essential to understand how they will respond to rising temperatures worldwide.

Sarah K. Richman

Ph.D. Student Conservation Studies, UC Berkeley

I study the community ecology of mutualism, asking how the structure of a species interaction network changes as cheating arises in a population. I am interested the role community context plays in promoting coexistence of cooperators, cheaters, and hosts. My work is done mostly in the field, using plants, pollinators, and nectar robbing bumblebees as a model system to answer these questions. Under certain ecological conditions, bumblebee pollinators will rob nectar from flowers rather than forage "legitimately" and thus minimize chances of pollinating. Little is known about the factors that promote this behavioral shift or whether the behavior is sustained. I want to know what contexts promote this behavior, the mechanism by which the change in behavior takes place, and its ultimate effect on community dynamics in the system.

Kelsey M. Yule

Ph.D. Student Ecology & Evolutionary Biology, Rice University

Broadly, I am interested in applying theoretical and empirical techniques to the study of the evolutionary ecology of species interactions. I am developing population and adaptive dynamics models to explore the consequences of indirect species interactions on mutualism stability and dynamics. I am especially interested in systems involving both mutualism and antagonism, such as systems in which two antagonistic species have a shared mutualist (ex: pollinator-seed disperser antagonism) and host-parasite-vector systems in which the parasite and vector have a mutualistic relationship. In the field, I am studying the interactions of desert mistletoe (Phoradendron californicum), a tractable parasite that is ecologically important and ubiquitous in the desert Southwest. A dioecious hemiparasite of a variety of leguminous trees and shrubs, desert mistletoe is vectored by a specialized mutualist seed-dispersing bird (Phainopepla nitens), which also feeds on insects, including mistletoe's pollinators.  Through modeling, experimentation, and observation, I hope to further our understanding of the dynamics of complex interactions.

Jessie Barker

Ph.D. Cornell University

B.Sc. Natural Sciences (Zoology), Cambridge University

I am a behavioral ecologist interested in the evolution of cooperation and conflict. My PhD research focused on the effect of competition on cooperation in social groups, with empirical work on both humans and paper wasps combined with game theoretic modeling. In my postdoctoral work in the Bronstein lab, I am continuing to study cooperation in both humans and social insects; I have ongoing empirical projects both in the lab, where I divide my time between bumblebee colonies and economic games with human participants, and the field, when I escape to observe honeybees in the Santa Catalina Mountains. The current focus of my research on insects is in the context of cooperation between species in pollination mutualisms, and I am also interested in investigating the similarities and differences in intra- and interspecific cooperation.

Nicole Rafferty

Ph.D., M.Sc., Zoology, University of Wisconsin, Madison

B.Sc. Ecology, Evolution, & Conservation, University of Washington

I’m interested in how climate change affects the timing of species interactions, particularly how shifts in flowering phenology affect interactions between plants and pollinators.  I've worked in a tallgrass prairie community and, more recently, in a sky island community in the Sonoran Desert.  I use a combination of experiments to directly manipulate phenology, long-term historical data to inform predictions, and observations that take advantage of natural variation in phenology to investigate both species-specific and community-level responses.

Post-doctoral Associates

Graduate Students

Dr. Judith L. Bronstein

Other Bronstein Laboratory Associates


Nick M. Waser

Professor Emeritus, University of California Riverside

Ph.D. Ecology & Evolutionary Biology, University of Arizona

I am Professor Emeritus from the Department of Biology at the University of California Riverside, where Mary Price and I split a position for 25 years.  I also am Adjunct Professor in the School of Natural Resources and the Environment here at the University of Arizona. Having done our PhD work in the EEB Department in the 1970s, Mary and I always hoped to return to Tucson, and we managed to do so in 2004.  We’ve enjoyed staying professionally active through associations with the U of A (including with Judie and her Lab group), through the Rocky Mountain Biological Laboratory (RMBL) in Colorado, and by various other hooks and crooks—we’ve even been able recently to teach field classes in Madagascar and Africa. I continue to do field work during summers at the RMBL, where I have studied many aspects of the interactions between flowering plants and their animal pollinators over the past 40+ years.  This work has touched on population and quantitative genetics, animal behavior, demography, and conservation biology, with its main focus being evolutionary ecology of the plant-pollinator interaction. When not working in the mountains I have enjoyed a long association with plants and animals of the Mojave, Sonoran, and Great Basin Deserts.

Dorit Eliyahu

Post-doctoral Research Associate

Ph.D. Entomology, North Carolina State University

M.Sc. Plant Protection, Hebrew University

B.Sc. Animal Sciences, Hebrew University

I am a chemical ecologist who usually works on chemical communication within and between insect species. In the Bronstein Lab, I work on a couple of projects that look at ecological aspects of interspecific interactions. One of my projects looks at the role of thrips in pollination of manzanita plants (Arctostaphylos spp.), some of which flower very early in the season. Another project examines the interactions between lycaenid caterpillars and ants.


Amy M. Iler

Post-doctoral Research Associate, University of Maryland & The Rocky Mountain Biological Laboratory

Ph.D. Evolution, Ecology, & Organismal Biology, The Ohio State University

B.Sc. Conservation Science, Muskingum University

As a field biologist, I seek to understand how anthropogenic change reshapes ecological processes.  I am interested in how species invasions and climate change alter species interactions, demographic processes, and ecological communities. Phenology, or the importance of the temporal niche, is a pervasive theme throughout my research.


Goggy Davidowitz

Associate Professor, Department of Entomology, University of Arizona

Ph.D. Ecology & Evolutionary Biology, University of Arizona

My broad area of interest is in how organisms adjust growth and development in response to environmental variation.  Specifically, I am focusing on the physiological mechanisms by which insects translate variation in diet quality and temperature, two environmental factors with strong effects on life histories, into phenotypic variation in body size and developmental time, two traits highly correlated with fitness.  In my work I emphasize the regulation of these traits at the level of the whole organism.  The complexity of the traits and the mechanisms that regulate them have led me to develop an integrative research program.  Currently, I am employing techniques from quantitative genetics, physiology, respirometry, endocrinology, ecology, evolutionary biology, behavior and elemental stoichiometry, combining lab, greenhouse and fieldwork.


Christopher Johnson

Ph.D., Biology, University of California, Los Angeles

B.Sc., Ecology & Evolutionary Biology, University of Arizona


My research focuses on the mechanisms by which mutualisms persist in the face of biotic interactions (e.g., competition, cheating) and abiotic environmental variability. I approach these issues using a combination of mathematical modelling and experimentation. From a theoretical perspective, I am investigating the role of competition for mutualistic benefits in the assembly and persistence of mutualistic communities as well as how mutualisms respond to environmental variability (e.g., in temperature). From an empirical perspective, I am studying how floral visitor diversity varies across the landscape and its effects on plant reproductive success using pointleaf manzanita (Arctostaphylos pungens) in the Madrean Sky Islands as a study system.

James L. Cunningham

Undergraduate Researcher

B.Sc. Ecology & Evolutionary Biology, University of Arizona

James has been working with the lab since 2012 with interests in the ecology of wild bees and the phenology of plant-pollinator networks.  He has played an active role in research projects with the lab in the Santa Catalina Mountains of Arizona and also in the Colorado Rocky Mountains.  He is also a passionate scientific communicator, sharing his knowledge of plants and insects to people of all ages, in both English and Spanish.

Heather M. Briggs

Ph.D. Candidate, University of California Santa Cruz

Plant-pollinator interactions.

Clare Aslan

Conservation Biologist, Arizona Sonora Desert Museum

Ph.D. University of California Santa Cruz

I am interested in the influence of environmental change on species interactions—how interactions function and fail under various anthropogenic influences, what factors can buffer systems from disruption, and what the conservation implications of interaction disruption may be. I focus on mutualisms, particularly seed dispersal and pollination, to address these interests. My field work takes place in Arizona, Hawaii, and California.

Mary V. Price

Professor Emeritus, University of California Riverside

Ph.D. Ecology & Evolutionary Biology, University of Arizona

I am Professor of Biology Emerita from the University of California, Riverside and Adjunct Professor in the School of Natural Resources and the Environment at the U of A. My interests include the evolutionary ecology of terrestrial animals and plants, especially in arid and montane ecosystems.  I have used desert kangaroo rats and their relatives as a model system for exploring factors that determine the number and phenotypic attributes of coexisting species in a community, and the nature of interactions between plants and granivores.  This work also encompasses conservation biology of endangered kangaroo rat species.  In addition, I have carried out long-term research on how the mutualistic interactions between plants and pollinators mold the evolution of flower morphology, plant mating patterns, and plant population dynamics.In addition to numerous publications on these topics in scientific journals, I have been stimulated in recent years to think of how long-term research in single places contributes to ecological knowledge.  This led to publication of a co-edited book, The Ecology of Place (University of Chicago Press) in 2010.  I am pleased that appreciation for the ideas in this book appears to be increasing steadily. The other book project that has occupied a large fraction of my recent time is as one of four authors (actually Nick Waser is also a “ghost author”) of a new university-level introductory biology textbook, Principles of Life (Sinauer/Macmillan), whose Second Edition just appeared.  Working on PoL has been a natural outlet for many years of teaching ecology at all levels—freshmen to PhD students—at UCR and elsewhere.

Gordon Smith

Ph.D. Student (Bronstein & Papaj Labs)

B.A. Biology, Williams College


I am interested generally in species interactions and insect behavior, especially in the context of pollination. Within this larger framework, my interests are currently divided between two broad sets of questions that I will likely explore to various degrees as I continue through the early stages of my PhD. First, since floral visitors differ in their morphology and behavior, plants are expected to have traits that preferentially attract / deter certain visitors. What are the mechanisms and consequences of this filtering, both from the plant perspective and from the insect perspective? Second, foraging insects hunting for flowers are also themselves being hunted by a wide variety of predators and parasitoids that may take advantage of flowers as productive hunting grounds. What influences the risk of predation, and how does pollinator behavior change in response to these risks, and how do these responses influence the plant/pollinator mutualism?

Bronstein Laboratory Alumni


+ Lyn Loveless (sabbatical 2012) – Professor, The College of Wooster.

+ Anurag Agrawal (sabbatical 2011) – Professor, Cornell University.

+ Monica Geber (sabbatical 2005) – Professor, Cornell University.

+ Bill Morris (sabbatical 2003) – Professor, Duke University.


+ Brigitte Marazzi - Swiss National Foundation postdoc 2009-2012; currently Research Associate at the Instituto de Botánica del Nordeste, Corrientes, Argentina.

+ Sevan Suni – PERT postdoctoral fellow 2010-2012; currently Darwin Fellow at University of Massachusetts Amherst.

+ Ruben Alarcon – PERT postdoctoral fellow 2004-2007; currently Assistant Professor at California State University Channel Islands.

+ Josh Ness – PERT postdoctoral fellow 2002-2005; currently Associate Professor at Skidmore College.

+ Nat Holland – NPS Ecological Fellow 2001-2003; currently Research Scientist at Unviersity of Houston.


+ Michele Lanan (Ph.D. 2010) – currently the Herbert Reich Chair of the Natural Sciences at Deep Springs College.

+ Kristen Potter (Ph.D. 2010) – currently postdoctoral fellow at Northern Arizona University.

+ Anne Estes (Ph.D. 2009) – currently postdoctoral fellow at University of Maryland School of Medicine.

+ Emily Jones (Ph.D. 2009) – currently Huxley Fellow at Rice University.

+ Alice Boyle (Ph.D. 2006) – currently Assistant Professor, Kansas State University.

+ Leif Richardson (M.Sc. 1999) – currently graduate student, Dartmouth College.

Caitlin Stern

Post-doctoral Researcher, University of North Carolina at Chapel Hill

Omidyar Fellow, Santa Fe Institute (starting September 2014)

Ph.D. Neurobiology & Behavior, Cornell University

A.B. Biology, Harvard University

My research focuses on the evolution of social behavior and mating systems, specifically how competition over reproductive opportunities affects the fitness consequences of association with kin versus non-kin. I address these questions using evolutionary game theory and population genetic modeling. My PhD research also included empirical work on the costs and benefits of living in a kin neighborhood for western bluebirds, which I studied at Hastings Reserve in the Carmel Valley, California, and I have a particular interest in social systems intermediate between the group territoriality of classical cooperatively breeding species and the exclusively solitary breeding of non-social species.

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