Two Mitochondrial Barcodes for one Biological Species: The Case of European Kuhl's Pipistrelles (Chiroptera).

Tommy Andriollo,Yamama Naciri,Manuel Ruedi,Wolfgang Arthofer

doi:10.1371/journal.pone.0134881

Abstract

The Kuhl’s pipistrelle (Pipistrellus kuhlii) is a Western Palaearctic species of bat that exhibits several deeply divergent mitochondrial lineages across its range. These lineages could represent cryptic species or merely ancient polymorphism, but no nuclear markers have been studied so far to properly assess the taxonomic status of these lineages. We examined here two lineages occurring in Western Europe, and used both mitochondrial and nuclear markers to measure degrees of genetic isolation between bats carrying them. The sampling focused on an area of strict lineage sympatry in Switzerland but also included bats from further south, in North Africa. All individuals were barcoded for the COI gene to identify their mitochondrial lineages and five highly polymorphic microsatellite loci were used to cluster them according to their nuclear genotypes. Despite this low number of nuclear markers, all North African nuclear genotypes were grouped in a highly distinct subpopulation when compared with European samples sharing the same mitochondrial barcodes. The reverse situation prevailed in Switzerland where bats carrying distinct barcodes had similar nuclear genotypes. There was a weak east/west nuclear structure of populations, but this was independent of mitochondrial lineages as bats carrying either variant were completely admixed. Thus, the divergent mitochondrial barcodes present in Western Europe do not represent cryptic species, but are part of a single biological species. We argue that these distinct barcodes evolved in allopatry and came recently into secondary contact in an area of admixture north of the Alps. Historical records from this area and molecular dating support such a recent bipolar spatial expansion. These results also highlight the need for using appropriate markers before claiming the existence of cryptic species based on highly divergent barcodes.

Highlights

DNA barcoding offers an aid for the identification and discovery of cryptic lineages by using a standardized mitochondrial gene, the cytochrome c oxidase subunit I (COI) for most animals [1]
All individuals were barcoded for the COI gene to identify their mitochondrial lineages and five highly polymorphic microsatellite loci were used to cluster them according to their nuclear genotypes
Two Barcodes for One Bat Species groups that are difficult to identify using classical morphologic approaches (e.g. [2, 3, 4]). One such group is the Chiroptera, which includes many closely related species that may share very similar morphologies and ecologies [5]. Such morphological similarities may result in overlooked diversity, as it has been suggested in European taxa such as the vespertilionids, in which the species number has increased by almost 50% since the emergence of DNA sequencing in taxonomy [6]

Summary

Introduction

DNA barcoding offers an aid for the identification and discovery of cryptic lineages by using a standardized mitochondrial gene, the cytochrome c oxidase subunit I (COI) for most animals [1]. [2, 3, 4]) One such group is the Chiroptera, which includes many closely related species that may share very similar morphologies and ecologies [5]. The Kuhl’s pipistrelle, Pipistrellus kuhlii (Kuhl, 1817), is perhaps the commonest bat species in the Mediterranean region [7, 8]. It apparently recently extended its range by recolonizing more temperate regions of Europe [9, 10]. A desert form living in arid areas of North Africa, P. k. deserti Thomas, 1915, has been considered as a full species based on its distinct morphology, but nuclear [13] and mitochondrial [8] markers showed that this morphotype evolved multiple times in different desert regions from typical P. kuhlii populations and is considered as a desert form of P. kuhlii [8, 13]

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Conclusion