Phylogeography and demographic history of Lacerta lepida in the Iberian Peninsula: multiple refugia, range expansions and secondary contact zones

Andreia Miraldo,Godfrey M Hewitt,Octavio S Paulo,Brent C Emerson

doi:10.1186/1471-2148-11-170

Abstract

BackgroundThe Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary. Recent phylogeographic studies have revealed Iberia as a complex of multiple refugia. However, most of these studies have focused either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida, whose distribution encompasses the entire Iberian Peninsula. We attempt to identify refugial areas, recolonization routes, zones of secondary contact and date demographic events within this species.ResultsResults support the existence of 6 evolutionary lineages (phylogroups) with a strong association between genetic variation and geography, suggesting a history of allopatric divergence in different refugia. Diversification within phylogroups is concordant with the onset of the Pleistocene climatic oscillations. The southern regions of several phylogroups show a high incidence of ancestral alleles in contrast with high incidence of recently derived alleles in northern regions. All phylogroups show signs of recent demographic and spatial expansions. We have further identified several zones of secondary contact, with divergent mitochondrial haplotypes occurring in narrow zones of sympatry.ConclusionsThe concordant patterns of spatial and demographic expansions detected within phylogroups, together with the high incidence of ancestral haplotypes in southern regions of several phylogroups, suggests a pattern of contraction of populations into southern refugia during adverse climatic conditions from which subsequent northern expansions occurred. This study supports the emergent pattern of multiple refugia within Iberia but adds to it by identifying a pattern of refugia coincident with the southern distribution limits of individual evolutionary lineages. These areas are important in terms of long-term species persistence and therefore important areas for conservation.

Highlights

The Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary
Even though the Iberian Peninsula is the best studied glacial refugium, most phylogeographic studies have focused on species that either have a narrow distribution within the region (e.g Chioglossa lusitanica [6], Lacerta schreiberi [9], Lissotriton boscai [11]) or involve species groups that, distributed across the entire region, generally have a genetic structure that relates to older cladogenetic events (e.g Podarcis spp. [12,13], Alytes spp [14], Oryctolagus cunniculus [15,16])
Mitochondrial and nuclear gene genealogies in Lacerta lepida provide evidence for a history of isolation and divergence in allopatry resulting in the diversification of six genetically and geographically distinct lineages

Summary

Introduction

Even though the Iberian Peninsula is the best studied glacial refugium, most phylogeographic studies have focused on species that either have a narrow distribution within the region (e.g Chioglossa lusitanica [6], Lacerta schreiberi [9], Lissotriton boscai [11]) or involve species groups that, distributed across the entire region, generally have a genetic structure that relates to older cladogenetic events In order to better understand the complex phylogeographic history of Iberian species, and the way they have responded to Pleistocene climatic oscillations, it is important to study species with distributions encompassing the entire Iberian Peninsula For this purpose we have used the ocellated lizard, Lacerta lepida (Daudin, 1802), as a model to study the impact of Pleistocene climatic changes in generating and structuring intraspecific genetic diversity on this regional scale. We assess the broader phylogeographic patterns within Lacerta lepida with the specific aims to i) clarify the distribution of mtDNA phylogroups; ii) identify refugial areas within these phylogroups during the glacial periods; iii) date the main demographic and evolutionary events within Lacerta lepida; and iv) identify secondary contact zones between the different phylogroups

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Discussion

Conclusion