Abstract
Populations at range limits are often characterized by lower genetic diversity, increased genetic isolation and differentiation relative to populations at the core of geographical ranges. Furthermore, it is increasingly recognized that populations situated at range limits might be the result of human introductions rather than natural dispersal. It is therefore important to document the origin and genetic diversity of marginal populations to establish conservation priorities. In this study, we investigate the phylogeography and genetic structure of peripheral populations of the common European wall lizard, Podarcis muralis, on Jersey (Channel Islands, UK) and in the Chausey archipelago. We sequenced a fragment of the mitochondrial cytochrome b gene in 200 individuals of P. muralis to infer the phylogeography of the island populations using Bayesian approaches. We also genotyped 484 individuals from 21 populations at 10 polymorphic microsatellite loci to evaluate the genetic structure and diversity of island and mainland (Western France) populations. We detected four unique haplotypes in the island populations that formed a sub-clade within the Western France clade. There was a significant reduction in genetic diversity (HO, HE and AR) of the island populations in relation to the mainland. The small fragmented island populations at the northern range margin of the common wall lizard distribution are most likely native, with genetic differentiation reflecting isolation following sea level increase approximately 7000 BP. Genetic diversity is lower on islands than in marginal populations on the mainland, potentially as a result of early founder effects or long-term isolation. The combination of restriction to specific localities and an inability to expand their range into adjacent suitable locations might make the island populations more vulnerable to extinction.
Highlights
There is a growing interest in the patterns and processes associated with geographical variation in population genetic structure across species’ ranges since these often shift, expand and contract over time [1,2,3,4]
We focused on mainland populations at the northwestern margin of the species distribution, i.e., close to the Channel Islands, and included a number of populations in south-western France to compare the observed divergence between island populations with divergence across the entire western France lineage
The parsimony network showed that WFR-H5 has a central position among French haplotypes and JER-H3 forms the centre of the cluster of Jersey and Chausey haplotypes, which are distinct from the rest of the mainland populations (Fig. 1B)
Summary
There is a growing interest in the patterns and processes associated with geographical variation in population genetic structure across species’ ranges since these often shift, expand and contract over time [1,2,3,4]. Marginal populations tend to show greater than expected isolation by distance and have lower genetic diversity than populations located within the species’ range [3] They are often of particular conservation interest [6,7]. It is increasingly recognized that isolated populations at the edge of species’ distributions might not have dispersed, or become isolated, naturally but instead might have been assisted by humans This has the potential to result in genetic admixture when animals are introduced from multiple source populations. It is important to establish the origin of marginal populations to be able to assign conservation priorities This is well exemplified by the changing status of the pool frog (Pelophylax lessonae) in Britain. The species is the focus of an active reintroduction program [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
