Landcover predicts isolation in Ambystoma salamanders across region and species

Anthropogenic modification of the landscape can have important consequences for dispersal of terrestrial organisms. If certain landcover types consistently act as barriers to movement, their occurrence could serve as a proxy for population isolation. We tested the fit of a general a priori landcover model on genetically-inferred isolation in ambystomatid salamander species. The landcover model included terms for pond size, geographic isolation, and amount of surrounding agriculture. In all cases, agriculture was associated with increased population isolation, while deciduous forest was almost always associated with decreased isolation. The full model described over 70% of the variation in a genetically-inferred measure of isolation in the system for which it was developed, and 30-45% of variation in novel systems. We suggest that landscape analyses can serve as a proxy for population isolation in ambystomatid salamanders. Our findings suggest that preserving well-forested regions without substantial agriculture will protect salamanders through increased population connectivity. These results have important implications for conservation, as genetic analyses are costly and time-consuming, and decisions to purchase or preserve land must often occur quickly. (C) 2009 Elsevier Ltd. All rights reserved.