Population subdivision of house mice (Mus musculus) in an agrarian landscape: consequences for control

In Argentinean agroecosystems, house mice (Mus musculus L., 1758) show a discontinuous distribution, with high abundances in farms but scarce abundance in crop fields. In our study area, the abundance of M. musculus could be affected by their movements among farms. We hypothesize that (1) M. musculus do not move among farms versus (2) M. musculus do move among farms. Furthermore, based on our second hypothesis, M. muscu/us move actively (hypothesis 2.1) or passively by human transport (hypothesis 2.2). Based on hypothesis 1, we predict that genetic subdivision will exist among farms and that genetic divergence will be independent of geographic distance. Based on hypothesis 2.1, genetic differentiation will be correlated with geographic distance. Based on hypothesis 2.2, genetic subdivision will be absent, or genetic differentiation will be related to human movements. We examined genetic variation among farms (n = 15) using five microsatellite loci and tracked the movements of 36 individuals from five farms with fluorescent powders. Populations of M. musculus showed genetic differentiation at both farm and shed scales. Genetic and geographic distances were significantly correlated. There was no evidence of passive movements of M. musculus. The movements of 36 M. musculus within farms, tracked with fluorescent powder, were short. According to these results, hypothesis 2.1 is favoured.