Data from: Do genetic structure and landscape heterogeneity impact color morph frequency in a polymorphic salamander?

Landscape heterogeneity plays an important role in population structure
and divergence, particularly for species with limited vagility. Here, we
used a landscape genetic approach to identify how landscape and
environmental variables affect genetic structure and color morph frequency
in a polymorphic salamander. The Eastern Red-backed Salamander, Plethodon
cinereus, is widely distributed in northeastern North America and contains
two common color morphs, striped and unstriped, that are divergent in
ecology, behavior, and physiology. To quantify population structure, rates
of gene flow, and genetic drift, we amplified 10 microsatellite loci from
648 individuals across 28 sampling localities. This study was conducted in
northern Ohio, where populations of P. cinereus exhibit an unusually wide
range of morph frequency variation. To test whether genetic distance was
more correlated with morph frequency, elevation, canopy cover, waterways,
ecological niche, or geographic distance, we used resistance distance and
least cost path analyses. We then examined whether landscape and
environmental variables, genetic distance, or geographic distance were
correlated with variation in morph frequency. Tests for population
structure revealed three genetic clusters across our sampling range, with
one cluster monomorphic for the striped morph. Rates of gene flow and
genetic drift were low to moderate across sites. Genetic distance was most
correlated with ecological niche, elevation, and a combination of
landscape and environmental variables. In contrast, morph frequency
variation was correlated with waterways and geographic distance. Thus, our
results suggest that selection is also an important evolutionary force
across our sites, and a balance between gene flow, genetic drift, and
selection interact to maintain the two color morphs.