The cost of mating and mutual mate choice in 2 role--reversed honey locust beetles

Situations where both males and females simultaneously exercise mate choice may be much more common than previously believed. Yet, experimental studies of mutual mate choice are rare as is information on the types of female traits that are favored by male mate choice. We first assessed the cost of mating to males under different feeding regimes in 2 honey locust beetles (Bruchidae, Megabruchidius spp.) where females actively search for and court males. Further, in a series of mate choice trials, we manipulated female mating status and male food provisioning to assess how male and female characteristics affected the outcome of male--female interactions. Mating carried substantial costs to males, but these costs were independent of food availability. Males generally showed a preference for large females but also for females that delivered a more vigorous courtship display. Moreover, males preferred virgin females in one species but nonvirgin females in the other species, and we provide data suggesting that this choice is adaptive. Female choice was restricted to a lower rate of female mate rejection of larger males in one of the species. Our results reveal a striking interspecific variation in mutual mate choice, even between these closely related species, and show that sexual selection in females can act on much the same types of traits that are commonly considered sexually selected in males, such as size-related traits and courtship vigor. This suggests that a preference for condition-dependent traits may be a commonality that is shared between mate choice by both sexes. Copyright 2011, Oxford University Press.