Phylogeographic structure and ecological niche modelling reveal signals of isolation and postglacial colonisation in the European stag beetle.

Karen Cox,Emanuela Solano,An Van Breusegem,Deborah Harvey,Niall Mckeown,Gloria Antonini,Arno Thomaes,Chung-Ping Lin

doi:10.1371/journal.pone.0215860

Abstract

Lucanus cervus (L.), the stag beetle, is a saproxylic beetle species distributed widely across Europe. Throughout its distribution the species has exhibited pronounced declines and is widely considered threatened. Conservation efforts may be hindered by the lack of population genetic data and understanding of the spatial scale of population connectivity. To address this knowledge gap this research details the first broad scale phylogeographic study of L. cervus based on mitochondrial DNA (mtDNA) sequencing and microsatellite analysis of samples collected from 121 localities across Europe. Genetic data were complemented by palaeo-distribution models of spatial occupancy during the Last Glacial Maximum to strengthen inferences of refugial areas. A salient feature of the mtDNA was the identification of two lineages. Lineage I was widespread across Europe while lineage II was confined to Greece. Microsatellites supported the differentiation of the Greek samples and alongside palaeo-distribution models indicated this area was a glacial refuge. The genetic endemism of the Greek samples, and demographic results compatible with no signatures of spatial expansion likely reflects restricted dispersal into and out of the area. Lineage I exhibited a shallow star like phylogeny compatible with rapid population expansion across Europe. Demographic analysis indicated such expansions occurred after the Last Glacial Maximum. Nuclear diversity and hindcast species distribution models indicated a central Italian refuge for lineage I. Palaeo-distribution modelling results also suggested a western refuge in northern Iberia and south-west France. In conclusion the results provide evidence of glacial divergence in stag beetle while also suggesting high, at least on evolutionary timescales, gene flow across most of Europe. The data also provide a neutral genetic framework against which patterns of phenotypic variation may be assessed.

Highlights

The stag beetle, Lucanus cervus L. (Coleoptera: Lucanidae) is distributed widely across Europe [1]
This study is the first phylogeographic investigation of stag beetle to incorporate both regional and fine scale sampling, and analysis of both mitochondrial DNA (mtDNA) and nuclear genetic markers. mtDNA analysis revealed a clear spatial pattern wherein most of the European range was dominated by a single clade
During the Last Glacial Maximum (LGM), possible habitat is predicted to be limited to the north-western corner of Greece but was connected with a larger habitat area in southern Albania

Summary

Introduction

The stag beetle, Lucanus cervus L. (Coleoptera: Lucanidae) is distributed widely across Europe [1]. Past and current forest management practices, such as logging, wood harvesting, and removal of old trees and dead wood, have had detrimental effects on saproxylic biodiversity [2, 3]. In light of such declines the stag beetle is listed as “near threatened” in the European Red List [3] and has been protected by the Habitats Directive of the European Union since 1992 [4]. On a broader geographical scale the identification of intraspecific Evolutionarily Significant Units (ESUs), their evolutionary history and spatial distribution provide vital information to optimise conservation strategies which minimise genetic diversity loss at species level [8]. In addition to providing information for spatial management strategies, such phylogeographic approaches can provide insight into how species have responded to historical climate change, and inform predictions of future climate change effects

Methods

Results

Conclusion