Patterns of gene flow and source‐sink dynamics in high altitude populations of the common toad Bufo bufo (Anura: Bufonidae)

Understanding patterns of genetic structure is fundamental for developing successful management programmes for deme‐structured organisms, such as amphibians. We used five microsatellite loci and DNA sequences of the mitochondrial control region to assess the relative influences of landscape (geographic distance, altitude and rivers as corridors for dispersal) and historical factors on patterns of gene flow in populations of the toad Bufo bufo in Central Spain. We sampled 175 individuals from eight populations distributed along two major river drainages and used maximum‐likelihood and Bayesian approaches to infer patterns of gene flow and population structure. The mitochondrial DNA data show closely‐related haplotypes distributed across the Iberian Peninsula with no geographic structuring, suggesting recent differentiation of haplotypes and extensive gene flow between populations. On the other hand, microsatellites provide finer resolution, showing that high altitude populations (> 2000 m) exchange lower numbers of migrants with other populations. The results of Bayesian estimates for recent migration rates in high altitude populations suggest source‐sink dynamics between ponds that are consistent with independent data from monitoring over the past 20 years. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 95 , 824–839.