European pond turtles represent a phylogeographically deeply structured complex of distinct taxa. Here, we use mitochondrial DNA sequences (cytochrome b gene) and eight polymorphic microsatellite loci to investigate genetic differentiation and gene flow of Sicilian, Corsican and Sardinian pond turtles and of subspecies involved in two secondary contact zones in the Pyrenean region and Southern Italy. Mitochondrial and microsatellite differentiation is largely concordant in populations from the core regions of the distribution ranges of the studied taxa. Both marker systems provide no evidence for gene flow between Sicilian pond turtles (Emys trinacris) and Southern Italian subspecies of E. orbicularis. By contrast, in the contact zones limited gene flow occurs between distinct subspecies of E. orbicularis. Although the Southern Italian contact zone is significantly older than the Pyrenean contact zone of Holocene age, patterns of asymmetric introgression are similar. Introgressive hybridization leads to the exchange of mitochondria, but microsatellite data indicate only a few individuals with mixed ancestry. This suggests that incipient isolating mechanisms maintain largely discrete nuclear genomic gene pools. Furthermore, this implies that Southern Italy acted as a hotspot rather than as a melting pot of genetic diversity during the last glacial. Pond turtles from Corsica and Sardinia are not differentiated from continental populations of the subspecies E. o. galloitalica, neither in the mitochondrial nor in the quickly evolving microsatellite markers. As the fossil record argues for a continuous presence of pond turtles on both islands since the Middle Pleistocene, this suggests that the native island populations became extinct and the extant turtles were later introduced by prehistoric settlers. The lack of genetic differentiation of pond turtles from Corsica and Sardinia supports the view that the subspecies described from these islands are not valid.

This review examines the ecological, economical, and public health significance of chironomids and provides examples of chironomid invasions via international shipping and the subsequent local and regional impacts. Dispersal and adaptation mechanisms as facilitators of chironomid invasions are presented, and control methods are discussed. Impacts ranged from increased nuisance occurrences to agricultural disruption. Anthropogenic activities including pollution-related decimation of aquatic benthic communities might allow introduction of invasive chironomids. Chironomids can inhabit many environments, including eutrophic lakes and wastewater treatment areas, and may accumulate contaminants in high concentrations. Health concerns include the association of chironomid egg masses with Vibrio cholerae, roles of chironomids as vectors for avian botulism, and effects of chironomid chemicals as human allergens. Therefore, the presence of new chironomid species in an environment may present threats to public health and local ecosystems.

Based on more than 1100 samples of Emys orbicularis and E. trinacris, data on mtDNA diversity and distribution of haplotypes are provided, including for the first time data for Armenia, Georgia, Iran, and the Volga, Ural and Turgay River Basins of Russia and Kazakhstan. Eight mitochondrial lineages comprising 51 individual haplotypes occur in E. orbicularis, a ninth lineage with five haplotypes corresponds to E. trinacris. A high diversity of distinct mtDNA lineages and haplotypes occurs in the south, in the regions where putative glacial refuges were located. More northerly parts of Europe and adjacent Asia, which were recolonized by E. orbicularis in the Holocene, display distinctly less variation; most refuges did not contribute to northern recolonizations. Also in certain southern European lineages a decrease of haplotype diversity is observed with increasing latitude, suggestive of Holocene range expansions on a smaller scale.

Hybrid zones are natural laboratories allowing insights in genetic processes like lineage diversification, speciation and introgression. Using large sampling, 15 microsatellite loci and a mitochondrial marker, we examined the Pyrenean contact zone of three pond turtle taxa (Emys orbicularis orbicularis, E. o. galloitalica, E. o. occidentalis). The Pyrenees are a biogeographically important region separating many lineages endemic to the Iberian Peninsula from their Western European counterparts. We discovered limited admixture, reflecting a complex biogeographic scenario. Simulations using Approximate Bayesian Computing supported that E. o. orbicularis invaded the Iberian Peninsula in the Holocene, circumventing the Pyrenees along the Mediterranean coast, and hybridized in the northern peninsula with the local coastal subspecies galloitalica, and to a lesser extent, with occidentalis. While E. o. occidentalis, and in particular E. o. orbicularis, expanded their ranges considerably during Holocene warming, E. o. galloitalica remained largely confined to its former Iberian refuge. Admixture among the three taxa is surprisingly low, and a future taxonomic investigation that includes the unstudied subspecies of E. orbicularis from North Africa, Eastern Europe and Asia has to determine whether their current status properly reflects their evolutionary divergence or whether certain taxa should be regarded as full species.

No abstract