Research Interests
My research seeks to integrate perspectives from ecology, evolutionary biology, and animal behavior. Much of my work is geared toward understanding how these aspects of population biology relate to and feedback on one another. Most often, I develop theory using mathematical and/or simulation models, though I often supplement this approach with the analysis of long-term field data. Below, I highlight themes that repeatedly come up in my work.
Ecology and the Evolution of Reproductive Behavior
In 1965, G. Evelyn Hutchinson published his book, The Ecological Theater and the Evolutionary Play. In it, he makes the argument that ecology sets the stage (i.e., selective environment) in which evolution plays out. It is now clear that this dependence is bidirectional: evolutionary dynamics can also feed back onto ecological processes (a feedback now referred to as eco-evolutionary dynamics). Much work considering this tight interplay between ecology and evolution has focused on traits with obvious ecological relevance, such as those controlling resource acquisition. Less attention has been paid toward traits that lack direct and obvious importance to ecology, such as reproductive traits.
In my own work, I have developed theory that builds on empirical evidence to make clear that ecology is a critical component to the evolution of reproductive traits. For decades, it has been known that extravagant sexual displays tend to increase predation risk; however, the consequences of this for eco-evolutionary dynamics remained unexplored. We showed that predation can drive complex eco-evolutionary dynamics in sexual displays, for example by driving evolutionary cycles in sexual displays (right). This work makes clear that eco-evolutionary dynamics are important in the context of sexual selection, not just for primarily “ecological” traits.
Biodiversity and species richness are important in both ecology and evolutionary biology. Evolutionary biologists tend to study the generation of diversity (speciation), whereas ecologists tend to study the maintenance of diversity (coexistence). Despite clear links, little work has been done to synthesize formal models of speciation genetics with coexistence theory.
Recent work interrogates such connections, finding that speciation and coexistence provide separate controls on diversification. For example, competitive exclusion may follow speciation. We find that ecological constraints are most important when fitness differences are large, assortative mating is strong, and competition is strong even between dissimilar phenotypes.
Some of my other work under this theme includes making clear the importance of the social environment for the evolution of divorce. One challenge to the evolution of divorce is that it tends to occur on low quality territories, thus making such territories overrepresented in the environment. Properly accounting for this feedback is essential for understanding the costs and benefits to divorce and may even be important for understanding why animals become attached to their mates. Further, I have shown that spatial structure mediates sexual conflict over extra pair copulations.
I am interested in the evolution of reproductive behavior broadly. Other work has shown that same-sex sexual behavior may persist through evolutionary time due to the adaptive evolution of indiscriminate mating. These results also have implications for understanding ancestral sexual behaviors. I have also explored the evolution of preference strength in the Fisher process.
Ecology and Evolution of Social Behavior
Another primary interest of mine is in social behavior. Understanding the evolution of cooperative behavior has been a cornerstone of evolutionary biology for decades. Perhaps as a consequence of this focus on its evolution, less is known about the ecological implications of social behavior. I have shown that social structure buffers density dependence occurring within social groups from negatively affecting the global population level. This was followed by a characterization of how processes occurring between social groups is a key driver of the population dynamics of social species.
In addition to developing theory, I collaborate with the Amboseli baboon research project, where I have focused on understanding the role of group size and group fissions in shaping social behavior in the baboons. In addition to this ongoing work, we have studied the collective behavior of group fissions in baboons, providing evidence that observed fission events are egalitarian. Collaborating with the baboon project has also provided exciting opportunities for linking theory with empirical work. For example, to argue that accelerated maturation upon exposure to a novel male in female mammals is a non-adaptive byproduct.
P.c. Beth Archie
These perspectives on the ecology of social behavior have also led to evolutionary insights. For example, I have shown that within-group density dependence and the dynamics of group and rank hierarchy formation may be important for understanding social evolution in carnivorans, and that abiotic conditions are critical to shaping the evolution of public goods production. Other projects have worked toward developing a formal definition of group fitness as well as how the ecology of cooperative foraging shapes the role that language plays in the evolution of human cooperation (a project led by former UNC undergraduate Megan Bishop).
Feedbacks across scales in structured populations
In addition to feedbacks across different subfields of population biology, I am also interested in understanding how different spatial scales feedback on one another. This theme comes up in a variety of contexts in my own work. For example, as alluded to above, I have demonstrated how understanding the population ecology of social species requires properly accounting for interactions between processes occurring within social groups and on social networks alongside processes occurring between social groups. Conceptually related to this perspective, I have worked to develop a general model of competitive metacommunities that underscores how regional outcomes can only be understood through feedbacks between local and regional processes.
