The ultimate and proximate mechanisms driving the evolution of long tails in forest deer mice.

Understanding both the role of selection in driving phenotypic change and its underlying genetic basis remain major challenges in evolutionary biology. Here, we use modern tools to revisit a classic system of local adaptation in the North American deer mouse, Peromyscus maniculatus, which occupies two main habitat types: prairie and forest. Using historical collections, we find that forest-dwelling mice have longer tails than those from nonforested habitat, even when we account for individual and population relatedness.

Nuclear and mitochondrial DNA reveal contrasting evolutionary processes in populations of deer mice (Peromyscus maniculatus).

We investigated a major geographic break in mitochondrial DNA (mtDNA) haplotypes in deer mice, Peromyscus maniculatus, by analysing spatial variation in a 491-bp fragment of the mtDNA control region from 455 samples distributed across a north-south transect of 2000 km in Western North America. To determine whether the mtDNA break was reflected in the nuclear genome, we then compared spatial variation in 13 nuclear microsatellites of 95 individuals surrounding the mtDNA break. Using a canonical correlation analysis we found that nuclear genomic variation was not correlated with mtDNA differentiation.