The contribution of Anatolia to European phylogeography: the centre of origin of the meadow grasshopper, Chorthippus parallelus

Abstract

Aim Chorthippus parallelus is one of the classic model systems for studying genetic structure and phylogeography in the Western Palaearctic. Here, we investigate the regional genetic differentiation of C. parallelus and evaluate the historical and evolutionary processes responsible for such genetic structuring, test the nature of the Turkish Straits system as a barrier to dispersal, and explore the contribution of Anatolian populations to the biodiversity of the Western Palaearctic. Location Western Palaearctic. Methods We incorporated sequence data from dense sampling of the phylogeographically important Anatolian region with both previous and newly obtained data of the nuclear fragment cpnl-1 and the mitochondrial fragment COI-tRNALeu-COII. In total, 1049 sequences of cpnl-1 from 33 regions were analysed to investigate the genetic diversity, genetic structuring and phylogeography of C. parallelus across its distributional range. The mtDNA region was additionally used to test whether the Turkish Straits system acts as a barrier. Results The analyses revealed that not all southern refugial populations of C. parallelus have contributed equally to the post-glacial recolonization of Europe. Four genetic clusters across the species' range were recovered: cluster A (eastern part of the Anatolian Diagonal); cluster B (western part of the Anatolian Diagonal); cluster C (Spain, Italy, southern Balkans, west part of Anatolia and Russia); and cluster D (covering the entire distributional range of the species). The Turkish Straits system has been a weak barrier to dispersal by C. parallelus, allowing gene flow from Anatolia to the Balkans. Main conclusions The current patterns of genetic structuring of C. parallelus were best explained by multiple expansion and contraction events. Anatolia has been well connected to the Balkans, contributing genetically to the establishment of central and northern European populations prior to the Holocene. The Anatolian refugium is suggested to be the centre of origin for Western Palaearctic C. parallelus diversity rather than a Balkan refugium.