title: Fine-scale population structure in a desert amphibian: landscape genetics of the black toad (Bufo exsul).
abstract: Environmental variables can strongly influence a variety of intra- and inter-population processes, including demography, population structure and gene flow. When environmental conditions are particularly harsh for a certain species, investigating these effects is important to understanding how populations persist under difficult conditions. Furthermore, species inhabiting challenging environments present excellent opportunities to examine the effects of complex landscapes on population processes because these effects will often be more pronounced. In this study, I use 16 microsatellite loci to examine population structure, gene flow and demographic history in the black toad, Bufo exsul, which has one of the most restricted natural ranges of any amphibian. Bufo exsul inhabits four springs in the Deep Springs Valley high desert basin and has never been observed more than several meters from any source of water. My results reveal limited gene flow and moderately high levels of population structure (F(ST) = 0.051-0.063) between all but the two closest springs. I found that the geographic distance across the arid scrub habitat between springs is significantly correlated with genetic structure when distance accounts for topography and barriers to dispersal. I also found very low effective population sizes (N(e) = 7-30) and substantial evidence for historical population bottlenecks in all four populations. Together, these results suggest that the desert landscape and B. exsul's high habitat specificity contribute significantly to population structure and demography in this species and emphasize the importance of considering behavioural and landscape data in conservation genetic studies of natural systems.
authors.affiliation: Center for Population Biology & Department of Evolution and Ecology, University of California, Davis, CA 95616, USA. ijwang@ucdavis.edu
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002025:Bufonidae / Q000145:classification / Q000235:genetics*; D002140:California; D003247:Conservation of Natural Resources; D003889:Desert Climate; D017753:Ecosystem; D004777:Environment; D051456:Gene Flow; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D018895:Microsatellite Repeats; D008957:Models, Genetic; D011157:Population Dynamics; D017422:Sequence Analysis, DNA