Environmental and topographic variables shape genetic structure and effective population sizes in the endangered Yosemite toad

Aim Describing the landscape variables that accurately reflect how environmental and topographic variations affect population connectivity and demography is a major goal of landscape genetics and conservation biology. However, few landscape genetics studies have quantified the relationships between landscape variables and effective population size (Ne), although Ne is a key conservation and population genetics parameter. In this study, I estimated genetic structure and effective population sizes in the Yosemite toad (Bufo canorus) and tested for associations with environmental and geographic variables. Location Yosemite National Park, California, USA. Methods I estimated FST, Dps and Ne using 10 microsatellite loci amplified from 781 individuals from 24 populations. I used three landscape variables (environmental variation, topography and slope) to generate geographic distance models and a series of regression analyses to identify the variables that contributed to genetic structure in this species. I also tested for correlations between Ne and a suite of variables, including geographic and genetic isolation, habitat suitability, elevation, temperature and precipitation. Results I found substantial variation in genetic distances between populations (FST = 0.0040.396, Dps = 0.0450.839) and in effective population sizes (Ne = 952). Environmental variation and slope played important roles in explaining variation in genetic distances, and precipitation variables were significantly correlated with Ne. Main conclusions These results show that environmental and topographic variables are both important for understanding population connectivity in B.similar to canorus and provide some of the first evidence, in any species, for a link between environmental variables and effective population size.