Genetic and Ecological Structure of a Population of Peromyscus leucopus

An extensive live-trapping system, consisting of 700 trap stations over 16 ha indicated that a demographic unit or demographically distinct subpopulation of Peromyscus leucopus can occupy an area as large as 13.5 ha or as small as 2.4 ha. The 2.4 ha demographic unit was located in a successional habitat and was characterized by consistently lower densities, winter extinction in four consecutive years, and a large number of immigrants relative to emigrants. Significant heterogeneity in allelic frequency and significant Fst values indicated that genetic structure occurred on the same scale. However, the units of genetic heterogeneity did not correspond to the demographic units.