Emys trinacris

Abstract: Geographic variation in the mtDNA haplotypes (cytochrome b gene) of 127 European pond turtles from Italy was investigated. Thirty-eight of the Italian samples were also studied by nuclear fingerprinting (ISSR PCR) and compared with samples from other parts of the range representing all nine currently known mtDNA lineages of Emys orbicularis. Our genetic findings were compared against morphological data sets (measurements, colour pattern) for 109 adult turtles from southern Italy. Italy is displaying on a small geographical scale the most complicated variation known over the entire distributional area of Emys (North Africa over Europe and Asia Minor to the Caspian and Aral Seas). The Tyrrhenic coast of the Apennine Peninsula, the Mt. Pollino area and Basilicata are inhabited by Emys orbicularis galloitalica, a subspecies harbouring a distinct mtDNA lineage. The same lineage is also found in Sardinia. Along the Adriatic coast of Italy and on the Salentine Peninsula (Apulia, southern Italy), another morphologically distinctive subspecies (Emys orbicularis hellenica) occurs, which also bears a different mtDNA lineage. A higher diversity of mtDNA haplotypes in the south of the Apennine Peninsula suggests that the glacial refugia of E. o. galloitalica and E. o. hellenica were located here. A further refuge of E. o. hellenica probably existed in the southern Balkans. The west coasts of the Balkans and Corfu have probably been colonized from Italy and not from the geographically closer southern Balkanic refuge. In Sicily, a third mtDNA lineage is distributed, which is sister to all other known lineages of Emys. Morphologically, Sicilian pond turtles resemble E. o. galloitalica. However, nuclear fingerprinting revealed a clear distinctiveness of the Sicilian taxon, whereas no significant divergence was detected between representatives of the other eight mtDNA lineages of Emys. Furthermore, nuclear fingerprinting provided no evidence for current or past gene flow between the Sicilian taxon and the mainland subspecies of E. orbicularis. Therefore, Sicilian pond turtles are described here as a species new to science. Some populations in Calabria and on the Salentine Peninsula comprise individuals of different mtDNA lineages. We interpret this as a natural contact. However, we cannot exclude that these syntopic occurrences are the result of human activity. For example, in other parts of Italy, the natural distribution pattern of Emys is obscured by allochthonous turtles. This could also be true for southern Italy. The discovery of the complex taxonomic differentiation in southern Italy requires reconsidering conservation strategies.

Abstract: 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.

Abstract: 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 .B y 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.

Abstract: Variation of the Sicilian pond turtle, Emys trinacris, is described, based on morphological data of more than 200 adult and immature turtles and mtDNA sequences of 31 new known-locality specimens. Emys trinacris is morphologically more variable than thought before. There exist pronounced population-specific differences. Adults are barely distinguishable from Emys orbicularis galloitalica. Hatchlings of E. trinacris are, however, significantly different patterned, allowing immediate species determination. Moreover, hatchlings of E. trinacris seem to be on average smaller and lighter than in E. orbicularis. This could be related with different reproductive strategies. Coloration polymorphism of adult Sicilian pond turtles comprises fair part of variation known in E. orbicularis. Thus, adult E. trinacris might have preserved the whole array of variation of the last common ancestor with E. orbicularis. We hypothesize that similarity of certain southern E. orbicularis subspecies and E. trinacris on one hand and pronounced differences in size, coloration and pattern of northern E. orbicularis subspecies on the other result from stabilising selection in the north. While dark coloration and large body-size seem to be beneficial in the north, light coloration and small size could be simply not disadvantageous in the south, allowing coloration polymorphisms in E. trinacris and southern E. orbicularis subspecies. Further, the term 'cryptic species' and its meaning in regard to species concepts and bar-coding is discussed. It is concluded that species delineation based on mtDNA bar- coding requires application of a Phylogenetic Species Concept. Under the Biological Species Concept, animal mtDNA is not always an ideal tool for delineating species boundaries because taxa with monophyletic mitochondrial gene trees are neither necessarily genetically isolated nor must represent the same Biological Species. Cryptic species are nothing special in nature because difficulties with their identification are due to deficits in cognitive abilities of man. This is illustrated by the fact that distinct live stages of 'cryptic species' may differ to various degrees from similar species, as is the case in hatchlings and adults of E. trinacris and E. o. galloitalica.