DISSERTATION RESEARCH: Evolution of Alternative Mating Tactics in the Yellow Dung Fly

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The process of evolution is expected to favor the single most successful behavioral tactic in a population and eliminate less successful options. Nevertheless, in some species, males adopt different behavioral tactics for acquiring mates, and it is unclear how males decide which tactic to adopt or what the reproductive consequences of this decision might be. In the yellow dung fly, some males compete with one another over access to females at breeding sites, whereas others search for feeding females in non-competitive environments. This study aims to understand the environmental and genetic factors that influence the choice of reproductive tactic in yellow dung fly males and how these alternative tactics are maintained within the same species. These results will help explain the wide diversity of animal traits observed within species throughout nature. Additionally, opportunities will be provided for high school and undergraduate students interested in biology to gain hands-on research experience by participating in data collection and analysis associated with this work.The co-occurrence of status-dependent alternative mating tactics is an example of extreme phenotypic variation persisting within a population. In addition to differences in mate securing behaviors and morphology, males of alternative tactics are also expected to differ in reproductive investment strategies due to tactic-specific variation in the degree of gametic competition that males face. The appropriate genetic model for understanding the evolution, maintenance, and expression of such phenotypic variation has long been the subject of intense debate. The "environmentally-cued threshold" model has recently emerged as a powerful quantitative genetics-based approach for investigating these long-standing questions. However, the difficulty of accurately quantifying lifetime fitness associated with each tactic has restricted its use in empirical studies. This research will overcome these obstacles by using large, experimental enclosures that simulate field conditions, as well as molecular analyses for paternity assignment, to assess lifespan and reproductive success associated with the size-dependent expression of alternative mating tactics in the yellow dung fly, Scathophaga stercoraria, which is a model system for behavioral ecology. All behavioral, morphological, and genetic data obtained from this research will be deposited into a public repository such as Dryad.