Experimental tests of spatial association and kinship in monogamous mice (Mus spicilegus) and polygynous mice (Mus musculus domesticus)

Abstract

The mound-building mouse (Mus spicilegus) and house mouse (Mus musculus domesticus) are closely related species that exhibit putative characteristics of social monogamy and mate-defense polygyny, respectively. Social behaviours and group composition in these species have been well studied in the laboratory under controlled conditions, and the purpose of our study was to examine conclusions drawn from laboratory data in less constrained seminatural enclosures. Specifically, we examined spatial associations and disassociations, which we used as indices of attraction and avoidance, respectively, in both species of mice. In each enclosure and for each species, we introduced small treatment groups of either 2 or 3 female kin (sisters) or 2 or 3 unrelated females, along with an equal number of unrelated males. Initial group composition and physical environments in our enclosures were similar for the two species, therefore we preformed a modified "common garden" experiment. We expected genetically based behavioural differences between species to be revealed. Mound-building mice exhibited strong spatial associations of male–female pairs, and also exhibited spatial avoidance of some of the other mice. House mice exhibited strong female groups of close kin that were significantly associated in space, but this species showed little spatial avoidance compared with mound-building mice. Our results support the idea of social monogamy in mound-building mice, where close reproductive associations of a paired male and female have been hypothesized from laboratory data. Our results also support more extensive evidence suggesting mate-defense polygyny in house mice.