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In systems with alternative reproductive tactics (ARTs), males have discrete behaviors and morphologies that allow them to optimize their reproductive success in relation to others in the population. Males with different phenotypes directly compete with one another for mates, providing unique opportunities for studying social interactions within a species. Using the Comanche Springs pupfish, Cyprinodonelegans, a species with three alternative reproductive tactics, I examine how male behaviors and social interactions influence the reproductive success of each tactic.

Previous studies suggest that large territorial males have high reproductive success, while satellite males and female mimics must intrude into territories in order to spawn. In a field study, I examined the social conditions that may facilitate satellite-male and female-mimic spawning. Males exhibiting these two tactics show different association patterns. Neither female mimics nor satellites preferentially associated with high-quality territorial males, but female mimics associated with females more than satellite males. Furthermore, unlike satellite males, female mimics rely upon deception of territorial males in order to garner matings. Territorial males express sex recognition of female mimics but this aggression towards female mimics is contextual, depending on presence of other potential threats or mates in a territory. Thus, the reproductive success of female mimics appears to depend upon the social environments.

To further examine the how alternative reproductive tactics correlate with reproductive success, I integrate behavioral studies with genetic techniques in a laboratory based experiment to show that territorial males sire more offspring than satellite males or female mimics. Further, the relative success of satellites and female mimics was influenced by demographic parameters (density and sex ratio), although demographic variation did not alter male aggressive behavior or quantitative measures of sexual selection. This study is the first to quantify success of males expressing alternative reproductive tactics in this genus. The results suggest that the effects of dynamic social environments on male behavior and reproductive success may play a role in the maintenance of alternative reproductive tactics in this system.


Dissertation, Lehigh University, 2008

Reprinted with permission of Proquest, Inc



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