In the present study the genetic structure of Dicentrarchus labrax (14 samples from the Mediterranean) was analysed at six microsatellite loci, in order to test the hypothesis that some enzymatic loci undergo selection between marine and lagoon habitat. Eight of the 14 samples were analysed at both microsatellite and allozyme markers. The analysis of the genetic variation among the Mediterranean samples showed that (i)&Fcirc;ST values obtained with the six microsatellite loci were much smaller than those obtained with the 28 allozymes and (ii) microsatellite loci seemed to reflect more the geographical proximity than an ecological one. Thirteen enzymatic loci exhibited moderate to high values compared with microsatellites. This was interpreted as evidence that these allozymes are non-neutral. However, only six loci seemed to be implicated in differentiation between marine and lagoon samples, the causes of selection being unknown for the others. A possible scenario of population dynamics of the sea bass between marine and lagoon habitat is suggested.

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The chironomid midges Belgica antarctica,\ud Eretmoptera murphyi (subfamily Orthocladiinae) and\ud Parochlus steinenii (subfamily Podonominae), are the\ud only Diptera species currently found in Antarctica. The\ud relationships between these species and a range of further\ud taxa of Chironomidae were examined by sequencing\ud domains 1 and 3–5 of 28S ribosomal RNA. The resulting\ud molecular relationships between B. antarctica and\ud E. murphyi, within Orthocladiinae, were highly supported\ud by validation analyses, confirming their position\ud within Chironomidae, as generated by classical taxonomy.\ud Within Podonominae, P. steinenii from the Maritime\ud Antarctic was more closely related to material from\ud sub-Antarctic South Georgia than to material from\ud Patagonia. Taking advantage of the availability of a\ud molecular substitution rate calculated for this gene in\ud Diptera, a dating of divergence between our study taxa\ud was tentatively established. The divergence dates obtained\ud were 49 million years (Myr), between B. antarctica\ud and E. murphyi, and 68.5 Myr between these species\ud and the closest Orthocladiinae taxon tested from Patagonia,\ud suggesting that B. antarctica and E. murphyi were\ud representatives of an ancient lineage. As both are endemic\ud to their respective tectonic microplates, their\ud contemporary distribution is, therefore, likely to have\ud been shaped by vicariance rather than dispersal

All species concepts are rooted in reproductive, and ultimately genealogical, relations. Genetic data are thus the most important source of information for species delimitation. Current ease of access to genomic data and recent computational advances are blooming a plethora of coalescent-based species delimitation methods. Despite their utility as objective approaches to identify species boundaries, coalescent-based methods (1) rely on simplified demographic models that may fail to capture some attributes of biological species, (2) do not make explicit use of the geographic information contained in the data, and (3) are often computationally intensive. In this article, we present a case of species delimitation in the Erebia tyndarus species complex, a taxon regarded as a classic example of problematic taxonomic resolution. Our approach to species delimitation used genomic data to test predictions rooted in the biological species concept and in the criterion of coexistence in sympatry. We (1) obtained restriction-site associated DNA (RAD) sequencing data from a carefully designed sample, (2) applied two genotype clustering algorithms to identify genetic clusters, and (3) performed within-clusters and between-clusters analyses of isolation by distance as a test for intrinsic reproductive barriers. Comparison of our results with those from a Bayes factor delimitation coalescent-based analysis, showed that coalescent-based approaches may lead to overconfident splitting of allopatric populations, and indicated that incorrect species delimitation is likely to be inferred when an incomplete geographic sample is analyzed. While we acknowledge the theoretical justification and practical usefulness of coalescent-based species delimitation methods, our results stress that, even in the phylogenomic era, the toolkit for species delimitation should not dismiss more traditional, biologically grounded, approaches coupling genomic data with geographic information.

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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. ResultsThe 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 transAegean 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 AegeanHellenic 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.