The effects of Pleistocene glaciations on the phylogeography of Melitaea cinxia (Lepidoptera: Nymphalidae)

Niklas Wahlberg,Ilik Saccheri

doi:10.14411/eje.2007.085

Abstract

Partial (600 bp) sequences of mitochondrial cytochrome oxidase I (COI) gene were used to infer the phylogeography of Melitaea cinxia (Lepidoptera: Nymphalidae) across the entire distributional range of the species, encompassing north Africa and Eurasia. Cladistic analysis of 49 distinct haplotypes (haplotype and nucleotide diversity were 0.95 and 0.027, respectively) revealed strong phylogeographic structure in M. cinxia, characterised by four major clades: Morocco; Western (Iberia, France, Italy); Central (central and northern Western Europe, Balkans, Greece, Anatolia, Levant); and Eastern (eastern Baltic, Urals, Iran, Siberia, China); separated by average pairwise distances of beween 2 and 6 percent. This pattern is consistent with the location of southern glacial refugia in the Iberian, Italian and Balkan peninsulas, as well as multiple eastern refugia. The Western clade is further structured into south-central Iberian, northern Iberian (and French) and southern Italian sub-clades; and the Eastern clade into Near Eastern and Far Eastern sub-clades; with weaker phylogeographical concordance within the Central clade, except for a large area in central and northern Western Europe which is monomorphic for COI haplotype. The Baltic and eastern Europe have been primarily colonized by the Far Eastern sub-clade, rather than the Central (Balkan) clade, highlighting the importance of including Near and Far Eastern populations in phylogeographic studies of Palearctic species. Maps showing the extent of clades and sub-clades suggest several regions of secondary contact and possible hybridization. Interspecific comparison of representative M. cinxia haplotypes supports a monophyletic origin of all M. cinxia.

Highlights

Quaternary climatic oscillations, punctuated by the Pleistocene glaciations, caused massive changes to the distributions of species in the Palaearctic (Hewitt, 2000, 2004; Schmitt, 2007)
The Pleistocene glaciations are likely to have increased the effective size of many populations at the species level, but the same process typically reduces genetic diversity at the regional level, usually in proportion to the distance from the parent refugium (e.g. Bernatchez & Wilson, 1998; Schmitt & Seitz, 2002; Michaux et al, 2003) and depending on the mode of contraction and expansion (Ibrahim et al, 1996)
The cytochrome oxidase I (COI) haplotypes sequenced for this study support a monophyletic origin of all Melitaea cinxia, and have revealed a high degree of phylogeographic structuring across the species range

Summary

Introduction

Quaternary climatic oscillations, punctuated by the Pleistocene glaciations, caused massive changes to the distributions of species in the Palaearctic (Hewitt, 2000, 2004; Schmitt, 2007). Repeated cycles of demographic contraction and expansion, into and out of pockets of climatically protected regional refugia, combined with individual ecologies, has led to varied patterns of present day phylogeographic concordance among species (Hewitt, 1999) These patterns indicate the existence of multiple glacial refugia, large differences in the ages of intraspecific divergences, and differential rates of post-glacial expansion among refugial populations. The overwhelming majority of intraspecific phylogeographic studies of Palaearctic species have focused on European populations of species that often have much wider distributions (Taberlet et al., 1998; Hewitt, 1999), meaning that our understanding of the history of Palaearctic species is based upon patterns found in only one-fifth of the landmass of this biogeographical region This is especially a problem for insects, for which the fossil and subfossil record is very poor (with the exception of beetles), and for which inference of evolutionary history is currently based entirely on molecular data, DNA sequences from the mitochondrial genome. Butterflies are no exception and the few published studies have been entirely restricted to western Europe

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