American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

2023 ASN Award for Distinguished Achievement in the Conceptual Unification of the Biological Sciences

Posted on by Ellen Ketterson

Judith L. Bronstein

Within community ecology, interactions in which both partners benefit from the interaction—mutualisms—are ubiquitous. Historically, however, species interactions were generally considered antagonistic, and many investigators ignored the possibility of a role for mutualisms in biological communities. Dr. Judith L. Bronstein has devoted her career to simultaneously exploring the breadth and intricacies of numerous types of mutualistic interactions and highlighting the critical roles that various mutualistic species interactions play in structuring biological communities to remedy this fundamental shortcoming in how we conceptualize the natural world.

Dr. Bronstein began her scientific career studying the iconic mutualism between figs (Ficus species) and their specialist pollinators, the agaonid fig wasps. Figs are pollinated by female fig wasps. However, the female wasps also oviposit only on ovaries in the pollinated flower, and the developing offspring consume the ovaries they occupy. This interaction starkly showcases a contradiction that is inherent in most mutualisms, that one or both interacting species pay some fitness costs in gaining the benefits of the interaction. For a fig tree, production of viable offspring because of the pollination services of fig wasp females entails the sacrifice of some ovaries to the wasps. Moreover, these interactions are not always beneficial, but rather shift between mutualism and antagonism depending on the ecological context in which the interaction occurs, and so can shift over time within the same community. Dr. Bronstein’s work is the exemplar of the rich complexity that must be considered in exploring the structure and dynamics of mutualisms.

Throughout her career, Dr. Bronstein’s empirical work has been rooted in the natural history of the interacting species under study, and she has used that natural history to frame critical tests of hypotheses that broadly inform larger conceptual issues. In addition to the fig/fig wasp interaction, she has studied other iconic mutualisms, including yuccas and their moth pollinators, ant-plant protection mutualisms, and various nectar feeding pollinator-plant interactions. Her empirical work has also framed these interactions in broader ecological and evolutionary contexts by exploring how other species (e.g., nectar robbers, herbivores, seed predators) influence the outcomes of interactions between plants and their pollinators, how mutualisms influence the overall population dynamics of the interacting species, competition among various mutualist partners, the role of individual variation in shaping costs and benefits for partners, the consequences of various life histories of pollinators to plant fitness components, the ecological and evolutionary consequences of cheaters in these interactions, and how various mutualisms may shape the responses of species to climate change. As this recitation highlights, her empirical work has integrated perspectives across many levels of biological organization, with mutualisms being the central focus.

In parallel with her empirical work, Dr. Bronstein has also augmented the conceptual framework for mutualistic interaction, which she has advanced in two forms. One is the formulation of mechanistic models of species interactions that have explored various ecological and evolutionary roles for mutualisms, including the ecological dynamics of multiple mutualists and cheaters, species coexistence, and the coevolution of mutualist partners and how ecological and evolutionary responses to antagonistic interactions with other species influence coevolution. The other is the publication of numerous conceptual reflections and reviews that have fundamentally reshaped how ecologists and evolutionary biologists think about mutualisms, and have placed mutualisms in a more rigorous context beside other types of species’ interactions. Her 1994 review paper in the Quarterly Review of Biology was instrumental in shifting the focus of ecologists toward the study of positive species interactions and away from exclusive emphasis on negative species interactions. A central tenet of this conceptual unification is the realization that most mutualisms are actually complex consumer-resource interactions in which the benefits for one or both species being consumed frequently outweigh the costs.

Dr. Bronstein has also contributed to the conceptual unification of the biological sciences through her dedicated service to the American Society of Naturalists. She has served as an officer at all ranks within the society. Most importantly, she served as Editor and then Editor-in-Chief of The American Naturalist. In addition, she is a Fellow of the Ecological Society of America and has received a distinguished service award from NSF and distinguished teaching Awards from the University of Arizona. She has also served the ecological and evolutionary committee through editorial positions with the Annual Review of Ecology and Evolution, the Quarterly Review of Biology, and Ecology, and as a Program Director and frequent panel member at NSF. Finally, she is a member of Board of Trustees and Executive Council and Designer of science exhibits at the Sonora Desert Museum, Tucson.

Based on her record of accomplishment in both empirical and theoretical studies of mutualisms and her service to the scientific community, the American Society of Naturalists is proud to award Dr. Bronstein with the 2023 ASN Award for Distinguished Achievement in the Conceptual Unification of the Biological Sciences.

—The Committee, Ellen Ketterson, chair, Ruth Shaw, and Mark Urban with major input from Mark McPeek and Monica Geber