Abstract

Although female multiple mating is widespread in insects, its adaptive significance remains poorly understood. To balance demonstrated costs to mating, females may obtain material and/or genetic benefits through multiple mating, and female mating strategies may have evolved to augment these benefits relative to costs: Material benefits are those in which females benefit through the use of resources controlled by males, the receipt of courtship food gifts, replenishment of sperm supplies, or a reduction in sexual harassment. Genetic benefits increase a female's fitness through enhanced genetic performance of her offspring, acting through the high intrinsic genetic quality of females' mates and/or through the interaction between female and male genomes. I performed a series of experiments designed to examine these issues in the decorated cricket, Gryllodes sigillatus. The first study evaluated the influence of both material and genetic benefits on female fitness by varying both the number of mating partners and the number of times that females mated. The results demonstrated that genetic benefits are more important than material benefits in determining female fitness. The second study considered the female preference for novel males over previous mates that is predicted by the enhanced fitness of polyandrous females. The third study utilized a quantitative genetics design to examine the mechanisms through which females obtain benefits. By finely partitioning variation in female fitness, I show that female G. sigillatus accrue genetic benefits primarily through the intrinsic genetic quality of their mates, and to a lesser degree, through the interaction of male and female genomes. The last study investigated sequential mate choice in decorated crickets. This study demonstrated that pre- and postcopulatory mate choice are reinforcing, as females prefer to mate with and accept more sperm from attractive males, However, this preference is independent of the attractiveness of former mating partners.