Long-distance geneflow and habitat specificity of the rock-dwelling coppertail skink, Ctenotus taeniolatus

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Abstract

Rock boulders or ‘bush-rocks’ provide essential habitat for many organisms and there has been interest in rehabilitating areas denuded of rock with artificial substitutes. We examine whether the density and size of bush rock influences the density of the coppertail skink (Ctenotus taeniolatus). The success of habitat rehabilitation is contingent on dispersal of rock-dwelling organisms into areas that have been remediated. To gauge the likelihood of this we characterize geneflow of coppertail skinks among discrete patches of rocky habitat associated with ridge tops. We genotyped 154 individuals from seven localities at six microsatellite DNA loci and from a subset of these individuals we obtained sequence data from the mitochondrial ND4 region. Our field survey established that lizard density was positively associated with the availability of suitably sized bush-rock (P < 0.001), highlighting the importance of maintaining this habitat element, or replacing it where it has been lost. Despite the presence of habitat features that might be presumed as barriers to dispersal for coppertail skinks, such as intervening gullies and dense vegetation, our genetic data demonstrated high levels of geneflow among rocky ridge tops. Levels of partitioning estimated by global FST were significant but low for both microsatellite (FST = 0.020) and mitochondrial data (FST = 0.113). Spatial autocorrelation of genotypic similarity supports our conclusion of regular longer-distance geneflow, and we infer lower levels of dispersal in juveniles than in adults. This study suggests that dispersal of coppertail skinks can be sufficient to naturally colonize areas of restored habitat.

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