Meeting Abstract
Sexual selection is believed to play a significant role in many cases of population divergence. While sexual selection is typically associated with female choice, males also make decisions when seeking mates. Natural selection is another significant source of population divergence. In migratory species, natural selection on phenology may lead to population divergence if one population migrates away from a resident population to breed, and therefore, the populations do not co-occur during breeding. We asked whether males differ in their courtship of females from diverged but closely related populations that differ in their migratory behavior, appearance, morphology, and phenology. We predicted that if male preference played a role in population divergence, males would significantly prefer females from their own subspecies. Alternatively in the absence of reinforcement, as subspecies do not co-occur during breeding season, resident males might court females regardless of subspecies or even prefer females from another subspecies. The dark-eyed junco, Junco hyemalis, is a small socially monogamous songbird that is comprised of both resident and migratory populations. The Carolina and Northern subspecies winter in the Appalachian Mountains, but breed separately after Northern juncos migrate to Canada in the spring. We conducted simulated courtship interactions, in which females were presented on Carolina males’ territories, and we recorded male visual and acoustic courtship displays. Each male was presented with a female of each subspecies on different days in random order and we compared courtship effort to determine whether males exhibited a preference for one subspecies or the other. Results are pending.
