Mating System Of Natural Populations Of The White-footed Mouse, Peromyscus Leucopus

The mating system of the white-footed mouse, Peromyscus leucopus has caused much confusion among evolutionary biologists interested in the social biology of the species. Some studies documented well-developed paternal behaviour (Horner 1947; McCarty and Southwick 1977; Hartung and Dewsburry 1979) and pair-activity (Mineau and Madison 1977). These results favour a monogamous mating system. Other studies proposed polyandry based on spatial association between adult males and females (Myton 1974). Still others argued for polygyny (Cicirello and Wolff, in press). All these studies are speculative.;I studied the mating system of the species with four different approaches. I first tested whether oestrous females would reject strange males and accept familiar males as mates, then examined whether paternal behaviour documented in previous studies might be unnatural behaviour caused by confined caging conditions. Meanwhile, I investigated association patterns of adult males and females in their natural habitats, and collected genetic information on mothers and their young to test the presence of multiple paternity within single litters.;Oestrous females readily accepted multiple-male insemination, with no indication of discriminating between familiar and strange males. Males did not provide paternal care of any sort in a large enclosure with 4 nest boxes and stopped interacting with the females once the copulation was over. The majority of experimental females showed aggression towards males except during their oestrus. In their natural habitats, females close to oestrus have more adult males nearby than females far from oestrus, indicating that adult males adjusted their position in relation to breeding status of females. Genetic analysis revealed that 25-100% of field-conceived litters were sired by multiple males. I conclude that promiscuity is a prevailing feature of the mating system of P. leucopus, with males exhibiting serial polygyny and females simultaneous polyandry. Adaptive significance of this mating system is discussed in relation to physiology, ecology and life history characters of the species