Increased molecular divergence of two endemic Trachelipus (Isopoda, Oniscidea) species from Greece reveals patterns not congruent with current taxonomy

In the present study, we employed three mitochondrial DNA genetic markers in a phylogenetic analysis aiming at the delineation of the relationships amongst nominal Trachelipus kytherensis populations, as well as between populations of this species and of Trachelipus aegaeus and a new form, occurring syntopically with the latter. Both the phylogenetic analysis and the genetic distances separating populations, show the presence of several distinct and well differentiated clades that undermine the monophyly of T. kytherensis. On the other hand, despite the insular distribution of T. aegaeus populations, their divergence is low and the monophyly of this taxon can be rescued by the inclusion of two more insular populations previously assigned to T. kytherensis. The patterns of genetic divergence among clades are only partially congruent with the geographic distribution of populations. The validity of taxonomic characters used so far in the genus appears to be questionable; therefore, a more comprehensive phylogenetic study at a population level is deemed necessary for understanding the divergence of Trachelipus lineages. © 2008 The Linnean Society of London

Testing phylogenetic hypotheses for reconstructing the evolutionary history of Dolichopoda cave crickets in the eastern Mediterranean

Aim  To investigate the molecular phylogenetic divergence and historical biogeography of cave crickets belonging to the genus Dolichopoda (Orthoptera, Rhaphidophoridae). Location  Caves in continental and insular Greece. Methods  We sequenced 1967 bp of mitochondrial DNA, corresponding to three fragments of the small and large subunit of the ribosomal RNA (16S and 12S rRNA, respectively) and to the subunit I of cytochrome oxidase (COI), to reconstruct phylogenetic relationships among all 30 known Greek species of Dolichopoda. Alternative hypotheses about the colonization of the Hellenic Peninsula by Dolichopoda species were tested by comparing the degree of discordance between species trees and gene trees under four plausible biogeographical scenarios. Results  The present study revealed a rather well resolved phylogeny at species level, identifying a number of clades that represent long-separated lineages and diverse evolutionary histories within the genus Dolichopoda. Two main clades were revealed within Hellenic–Aegean species, identifying a north-western and a south-eastern species group. Based on Bayesian analysis, we applied a relaxed molecular clock to estimate the divergence times between the lineages. The results revealed that the origins of eastern Mediterranean lineages are much older than those of previously studied western Mediterranean Dolichopoda. Tests of alternative biogeographical hypotheses showed that a double colonization of the Hellenic Peninsula, following separate continental and trans-Aegean routes during the Messinian stage, best accounts for the present distribution of Greek Dolichopoda species. Main conclusions  Reconstruction and biogeographical hypothesis testing indicated that the colonization of Greece by Dolichopoda species comprised two episodes and two different routes. The southern lineage probably arose from a trans-Aegean colonization during the Messinian salinity crisis (5.96–5.33 Ma). The northern lineage could be the result of dispersal from the north through the Balkan Peninsula. The opening of the Mid-Aegean Trench could have promoted an initial diversification within the uprising Anatolian Plateau, while the Messinian marine regression offered the conditions for a rapid dispersal through the whole Aegean–Hellenic region. In addition, climatic events during the Plio-Pleistocene may have been responsible for the speciation within each of the two different phylogeographical units, principally attributable to vicariance events