Jacqueline Dillard: Dissertation Research: Cooperation and the Covariance between Genetic Monogamy and Limited Dispersal

Overview The primary goal of this proposed research is to investigate the relationship between mating systems and social systems, specifically in light of recent debate surrounding the monogamy hypothesis. This hypothesis proposes that lifetime genetic monogamy, by increasing the relatedness between siblings, was a key feature in the evolution of family-based cooperative breeding and eusocial societies. Some theoretical models, however, predict a reduction of help with increased local relatedness due to increased competition with relatives. In addition, the selective factors favoring monogamy also tend to favor cooperation, and the observed correlation between these two traits may not be due to high sibling relatedness per se. With my first objective, I will assess genetic population structuring and dispersal in a population of bess beetles to determine the consequences of mating and dispersal strategies on cooperative and competitive interactions. For my second objective, I propose several experiments to determine if the same selective pressures influence both genetic monogamy and delayed dispersal. Specifically, I test the hypothesis that resource distribution may drive both reduced extra-pair paternity and increased delayed dispersal simultaneously using a field enclosure experiment as well as correlational field data of dispersal and paternity. Intellectual Merit Following the debut of inclusive fitness theory, W. D. Hamilton, suggested that cooperation would be favored in species with limited dispersal because relatives would be more likely to interact. Recent theoretical work, however, suggests that high local relatedness may reduce inclusive fitness through if relatives compete. The first objective of this project will be one of the first attempts to empirically investigate local relatedness and its consequences for cooperation and competition in a cooperative beetle with limited dispersal. The second objective in this study will test the novel hypothesis that certain environments may favor both monogamy and cooperation simultaneously, leading to a correlation between mating and social system that is consequential rather than causal. Conceptually, this hypothesis suggests that the terms in Hamilton's Rule (rB-C>0) may covary in certain environments. Here, I test whether a single ecological variable, specifically low resource density, reduces both the costs (C) of helping (by increasing the costs of dispersal) while simultaneously increasing the relatedness between helpers and their siblings (r) by reducing extra-pair paternity. This finding would suggest that the terms in Hamilton's Rule are not be modular, but rather covary under certain conditions, changing the way we understand both the correlated evolution of social and mating systems as well as the association between relatedness and cooperation. Broader Impacts The proposed research will significantly enhance my own professional development by allowing me to learn new computational and field techniques, test novel ideas developed during my dissertation. I will also gain valuable experience in preparing and presenting the results of this work for both publications and presentations at national and international conferences. In addition, this project will facilitate training and mentoring of several undergraduate students in field techniques and the scientific process. I also plan to disseminate not only the results of my own work, but also that of the rest of the researchers in the University of Kentucky Biology Department, during a large-scale, open-house community engagement project that I am developing in collaboration with the director of the UK Ecological Research and Education Center, Dr Phil Crowley, and fellow graduate student, Luc Dunoyer.