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Copulation Duration in a Promiscuous Leaf Beetle

Hybrid zones provide an excellent system to study the evolution of reproductive barriers, as they allow for the close observation of species interactions. An understudied aspect of sexual interactions in hybrid zones is the effect of heterospecific mating on copulation duration. In this study, I looked at the outcomes of heterospecific mating frequency on copulation duration and female lifespan of the beetle Chrysochus cobaltinus, which forms a hybrid zone with the closely related C. auratus in south-central Washington State. I found that heterospecific matings had a significantly longer copulation duration than conspecific matings and that conspecific matings preceded by heterospecific matings were significantly longer than conspecific matings preceded by other conspecific matings. The overall frequency of heterospecific matings, number of matings, total time mated, and the identity of the males, had no significant effects on the female’s lifespan. These findings invite further research on male-female interactions in hybrid zones, as they suggest that male preference could possibly be a significant factor in copulation duration in these beetles.