Mountainous genus Anterastes (Orthoptera, Tettigoniidae): autochthonous survival across several glacial ages via vertical range shifts

Abstract

Although the high‐latitude range margins in Europe and North America are intensively studied, attention is gradually turned towards the taxa/populations inhabiting glacial refugia. Here, we evaluate the genealogical history of the cold‐adapted Anatolio‐Balkan genus Anterastes especially to test the possible effects of intrarefugial vertical range shifts during climatic oscillations of the Quaternary. Using concatenated data from sequences of COI+16S and ITS1–5.8S–ITS2, intrageneric relationships and the time of speciation events were estimated. Thirteen different demographic analyses were performed using a data set produced from sequences of 16S. Different phylogenetic analyses recovered similar lineages with high resolution. The molecular chronogram estimated speciation events in a period ranging from 5.60 to 1.22 Myr. Demographic analyses applied to 13 populations and five lineages suggested constant population size. Genetic diversity is significantly reduced in a few populations, while not in others. Fixation indices suggested extremely diverged populations. In the light of these data, the following main conclusions were raised: (i) although glacial refugia are the biodiversity hotspots, species level radiation of the cold‐adapted lineages is mainly prior to the Mid‐Pleistocene transition; (ii) heterogeneous topography provides refugial habitats and allows populations to survive through vertical range shifts during climatic fluctuations; (iii) prolonged isolation of refugial populations do not always result in reduced intrapopulation diversity, but in high level of genetic differentiation; (iv) the cold‐adapted lineages with low dispersal ability might have not colonised the area out of Anatolian refugium during interglacial periods; and (v) populations of invertebrates may have restricted ranges, but this does not mean that they have small effective population size.