International Research Fellowship Program: Indirect Genetic Effects and the Evolution of Cannibalism

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0700452BleakleyThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Bronwyn H. Bleakley to work with Drs. John Hunt and Allen Moore at the University of Exeter in the United Kingdom, and with Dr. Stephen Shuster at Northern Arizona State University in the US.An individual's behavior may result not only from its own genes and the environment in which is resides, but may also reflect genes carried in the individual's social partners. The effects of genes carried in a social partner on the behavior of another individual are termed "indirect genetic effects." Indirect genetic effects are one way of generating "interacting phenotypes," where an individual's phenotype can only be described in the context of an interaction. Indirect genetic effects are predicted to be particularly important in the evolution of social behavior because they may alter the way selection operates on individuals, as well as generate social selection. The relative effects of social selection have only rarely been partitioned out in natural populations and the impacts of indirect genetic effects on the strength of social selection have never been documented. Cannibalistic behavior is an interacting phenotype, is likely to reflect indirect genetic effects, and is predicted to generate social selection, but has never been explored in this context. We are developing the first quantitative genetic model describing the evolution of cannibalism in the context of indirect genetic effects and utilizing a natural system, the Socorro Isopod Thermosphaeroma thermophilum, to experimentally test the model. We are designing a quantitative genetic model that considers the genetic variances and covariances underlying body size and cannibalism, the intensity and direction of sexual and social selection operating on these traits, and the frequency and strength of intraspecific interactions that may influence the expression and evolution of these traits via indirect genetic effects. We are using the model to mathematically manipulate the genetic covariance structure between cannibalism and body size and the intensity of social selection to predict the impact of these factors on the rate of evolution of cannibalism. We are concurrently obtaining empirical measurements of interacting and non-interacting traits (body size and cannibalism) and their genetic variances and covariances in lab populations of T. thermophilum; generating predictions for the relative influence of social selection on the evolution of these isopods; and determining if the genetic covariance between body size and cannibalism varies across existing experimental populations, allowing for differential response to selection.