An unusual phylogeography in the bushcricket Ephippiger ephippiger from Southern France

Abstract

Pleistocene glaciations have played a major role in species divergence. The bushcricket Ephippiger ephippiger shows unusual patterns of intraspecific variation in multiple traits across Southern Europe. This is centred in Southern France, and evidence implies that it results from secondary contact after differentiation in Pleistocene refugia. However, the possible time scales involved, locations of the refugia and patterns of expansion remain obscure. This study sequenced the COII (507 BP) and cyt b (428 BP) mitochondrial genes to examine the intraspecific phylogeography of Western European samples of E. ephippiger. A minimum evolution tree revealed little resolution between described subspecies of E. ephippiger. Strikingly, populations from the Pyrenees and Mediterranean coastal region contained a complex genetic structure corresponding to major river valleys, independent of the traditional taxonomy. Samples of the subspecies E. e. vitium formed a distinct clade, perhaps supporting their taxonomic status. However, other forms (cruciger and cunii) were not genetically distinct, which is surprising given differences in their morphology and behaviour. The extent of the genetic divergence between Pyreneen valleys is unexpectedly deep, with average Tamura-Nei distances of around 14% (net distances of 11%) separating the main clades of coding COII sequences. Cyt b showed a similar pattern, but was confounded by some non-coding probable pseudogenes. If a conventional insect molecular clock is applied, these cryptic clades must predate the Pleistocene, and hypotheses for their history are discussed. However, mtDNA divergence in Ephippiger is not evolving in a clock-like manner, because a likelihood ratio test rejects clock assumptions for the COII sequences.

The origin of theChorthippus parallelushybrid zone: chromosomal evidence of multiple refugia for Iberian populations

“…In their review of the molecular biogeography of a number of fish, amphibian, reptile, invertebrate and plant species, they argue instead that the region contained ‘refugia within refugia’ that were capable of supporting genetically diverse populations. Spooner & Ritchie (2006) reached similar conclusions from their study of the phylogeography of the western European populations of the bushcricket Ephipigger ephipigger : the populations from the Pyrenees and Mediterranean coastal region show unexpected genetic divergence for mitochondrial DNA traits, which is difficult to explain solely under the standard general hypothesis of single southern refuge and genetic introgression following secondary contact motivated by the last glaciation. Our results are consistent with this concept of multiple refugia, although their precise locations in the case of C. parallelus have not yet been determined.…”

Discordances between phylogenetic and morphological patterns in alpine leaf beetles attest to an intricate biogeographic history of lineages in postglacial Europe

“…The role of the Balkans and the Pyrenees is highlighted in the Oreina AGS biogeographic history through their roles in hosting the most ancestral refugial populations (represented by M1 and M2, respectively). As for other insect groups (Spooner & Ritchie 2006;Varga & Schmitt 2008;Rousselet et al 2010), the importance of the Pyrenean range was in addition inferred for clade M6 (Figs 4, 5 and 7). The Pyrenees as well show recent connections with nearby massifs, such as the Cantabric range, Massif Central and Apennines (clades M6a,b,c).…”

Dispersal differences predict population genetic structure in Mormon crickets

“…1999; Pook et al . 2000), glacial events during the Quaternary are likely to have reinforced lineage distinctions by influencing their current distribution, as has been found in some avian species (Avise & Walker 1998) and European bushcrickets (Spooner & Ritchie 2006). Repeated Pleistocene glacial cycles are thought to have promoted divergence as species were displaced from the Rockies and other areas in the United States into refugia (Hewitt 2000; Brunsfeld et al .…”