Sperm competition and alternative mating tactics in bluegill sunfish

grantor: University of TorontoSperm competition is one of the most active areas of research in mating systems and behavioural ecology. This thesis examines sperm competition in the context of the alternative male mating tactics in bluegill sunfish (' Lepomis macrochirus'), and contains two chapters. Chapter one examines the fertilization success of alternative mating tactics under sperm competition, and tests the hypothesis that sneaks win under sperm competition, as predicted by the Sneak-Guard model. Using microsatellite DNA fingerprinting, statistical models, and behavioural measures in the field, I provide the first confirmation of this prediction. Chapter two examines the sperm investment strategies and mechanisms by which sneaks win. I identify differences between the male mating tactics in their investment in gonads, sperm characteristics, ejaculate sperm density, and competitiveness. Overall, this thesis provides a measure of fertilization success under sperm competition and an explanation as to how this success can be obtained.M.Sc