Inbreeding avoidance behaviour of male bank voles in relation to social status

Since inbreeding can result in reduced offspring fitness, female animals often avoid mating with close relatives. In theory, males may also avoid inbreeding under certain conditions, notably if alternative mating opportunities are available at low cost. Hence competitively successful or dominant males may be more likely to avoid inbreeding because they have more mating opportunities. We tested these predictions in a promiscuous rodent with clear male dominance relationships, the bank vole, Myodes glareolus. Specifically, we quantified behavioural responses in relation to sibling and nonsibling females presented simultaneously under controlled experimental conditions. Male bank voles spent significantly less time in proximity to sibling than nonsibling females. However, contrary to theoretical predictions, male preference for nonsibling females did not differ significantly according to social status. Additionally, we found that male bank voles showed no preference for females as a function of either their body mass or age. Our findings suggest that regardless of their social status, male bank voles find nonsibling females more attractive than siblings. We discuss these results in relation to recent evidence of male status-dependent mate choice.