Evolutionary biology of female multiple mating in the red flour beetle, Tribolium castaneum.

摘要

Female multiple mating is a widespread phenomenon observed in diverse taxa ranging from mammals to invertebrates. Why this behavior persists in spite of no obvious benefits of mating to females, needs to be understood. Direct (material) or indirect (genetic) benefits from mating with different males may promote female multiple mating. This study examined hypotheses for mechanisms that promote female multiple mating using the red flour beetle, Tribolium castaneum.;The specific goals of this work were to (1) study female multiple mating behavior, (2) seek evidence for both direct and indirect benefits of multiple mating, and (3) to inspect the role of female mate choice in evolutionary biology of female multiple mating in this species.;Female red flour beetles mated with 5 different males in a single hour on average, however mating with multiple males did not enhance egg/adult offspring production, female life span or fertility retention. As long as females received at least two mating opportunities, number of mating partners did not significantly affect offspring production. High incidence of infertile first copulations may explain the high mating frequency of virgin females but does not account for the observed high mating frequency of non-virgin females.;T. castaneum females exhibit both pre- and post-copulatory mate choice. Infection with rat tapeworm Hymenolepis dimunita diminishes male fitness therefore this disease was used as an indicator of male quality. There was no evidence for pre-copulatory or post-copulatory choice against diseased, hence 'poor' quality males. Female multiple mating affected offspring quality. Thus, in a competitive environment multiply mated females produced better quality sons and poorer quality daughters as compared to singly mated females. Further offspring of multiply mated females gained genes for both viability as well as attractiveness. These data suggest a genetic cost to multiple mating females in the form of less fit daughters. The mechanism creating this pattern needs to be unraveled.;In summary, this dissertation showed both direct and indirect benefits of female multiple mating. It also showed that indirect or genetic costs and benefits of mating may play an important role in maintaining female multiple mating.