Pair-bonding behaviour of the sister species Microtus lusitanicus and M. duodecimcostatus

Abstract

Monogamous mating systems can be inferred by analysis of social behaviour, for example pair-bonding. We studied the Iberian sister species Microtus lusitanicus and Microtus duodecimcostatus. On the basis of morphological, reproductive, and ecological characteristics, but not behavioural studies, these voles are regarded as monogamous species. Pair-bonding behaviour was inferred by use of partner preference tests using chemical stimuli. Two scenarios were considered: in the first we examined whether the member of a breeding pair prefers chemical stimuli from its partner or from a sexually experienced stranger, simulating a widow/widower of the population, while in the second scenario we assessed whether there was a preference for chemical stimuli from its partner or from a sexually naive stranger, mimicking an immigrant individual. Results support a social monogamous mating system for both species and reveal a significant female preference for the male partner, rather than a stranger. Conversely, male preference differed, depending on the sexual status of the female strangers. When the stranger was sexually experienced, a significant preference for its partner was observed, whereas in the presence of a sexually naive female stranger no significant preference for the female partner was revealed. These results suggest rare male extra-pair mating in M. lusitanicus and M. duodecimcostatus.