Patterns of speciation in Dolichopoda cave crickets (Orthoptera, Rhaphidophoridae)

This study focuses on the phylogenetic relationships among ninety percent of known Dolichopoda species (44 out of 49); primarily a Mediterranean genus, distributed from eastern Pyrenees to Caucasus. A total of 2,490 base pairs were sequenced corresponding to partial sequences of one nuclear (28SrRNA) and three mitochondrial genes (12S, 16S and COI). A relaxed molecular clock, inferred from Bayesian analysis was applied to estimate the divergence times between the lineages using well dated palaeoevents of the study areas. Molecular substitution rates per lineage per million years were also obtained for each analysed gene. Based on the nearly complete species phylogeny, temporal patterns of diversification were analysed using Lineage-Through-Time plots and diversification statistics. Alternative hypotheses about the colonization of western Mediterranean by Dolichopoda species were tested by means of Approximate Bayesian Computation analysis and by comparing the degree of discordance between species trees and gene trees under four plausible biogeographic scenarios. Both phylogenetic reconstruction and results from the biogeographical hypotheses test suggested that the current distribution of Dolichopoda species has been essentially shaped from the palaeogeographic and climatic events occurred in the Mediterranean region, starting from Late Miocene up to the Plio-Pleistocene. Our results suggest that the current distribution of Dolichopoda can be explained by a combination of both vicariance and dispersal events, with many processes occurring in ancestral epigean populations before the invasion of the subterranean environment.