Landscape models for nuclear genetic diversity and genetic structure in white-footed mice (Peromyscus leucopus)

Dramatic changes in the North American landscape over the last 12 000 years haveshaped the genomes of the small mammals, such as the white-footed mouse (Peromyscusleucopus), which currently inhabit the region. However, very recent interactions ofpopulations with each other and the environment are expected to leave the most pronouncedsignature on rapidly evolving nuclear microsatellite loci. We analyzed landscapecharacteristics and microsatellite markers of P. leucopus populations along atransect from southern Ohio to northern Michigan, in order to evaluate hypotheses aboutthe spatial distribution of genetic heterogeneity. Genetic diversity increased to thenorth and was best approximated by a single-variable model based on habitat availabilitywithin a 0.5-km radius of trapping sites. Interpopulation differentiation measured byclustering analysis was highly variable and not significantly related to latitude orhabitat availability. Interpopulation differentiation measured as F_STvalues and chord distance was correlated with the proportion of habitat intervening, butwas best explained by agricultural distance and by latitude. The observed gradients indiversity and interpopulation differentiation were consistent with recent habitatavailability being the major constraint on effective population size in this system, andcontradicted the predictions of both the postglacial expansion and core-peripheryhypotheses.