ABSTRACT
Aim: Chorthippus parallelusis 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. parallelusand 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 fragmentcpnl-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. parallelusacross 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 ofC. 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.