Potential female mate choice in a male dominated system: the female capybara, Hydrochoerus hydrochaeris

Abstract

Abstract Capybaras, Hydrochoerus hydrochaeris (Rodentia: Caviidae: Hydrochoerinae), show a strict social hierarchy among males, wherein the top-ranking male gains preferential access to females. Despite minimal sexual size dimorphism, males have a prominent scent gland on their snouts that is greatly reduced in the females. Top-ranking males have a larger gland and mark more frequently than subordinate males. This species also shows a moderately complex courtship that seems to be modulated by female behavior. In this study, we evaluated several components of courtship, as well as the females’ interactions with males during and outside courtship, in relation to the hierarchy rank of males. We found that subordinate males engaged in longer courtships than top-ranking males. However, there was no difference in the number of mount attempts or the success rate of these mounts as a function of the social status of the male, despite the longer courtship performed by subordinate males in comparison to top-ranking males. Outside courtship, females directed the same number of social interactions to males regardless of status. However, during courtship, females avoided copulation by subordinate males both directly and indirectly by encouraging courtship disruption by higher-ranking males. Females’ avoidance of subordinates may force these males to invest a higher amount of effort in courtships, thus engaging in longer courtships, yet achieving similar mount success as top-ranking males. We show that the original assumption of male hierarchy as the main mechanism of reproductive distribution is incomplete, and female mate choice plays an important role in determining which males reproduce.