Nuclear genetic variation and population structure were assessed in 140 individuals from 16 populations across the range of the Danube crested newt (Triturus dobrogicus) using 40 enzyme loci. Intraspecific hybridization with other crested newt species (Triturus carnifex, T. cristatus, T. macedonicus and T. arntzeni) affected 33 individuals in 11 populations at the range edge and reduced operational sample size to 107 T. dobrogicus in 14 populations. Allele diversity was high, and we inferred a high level of gene flow among T. dobrogicus populations, possibly associated with flooding conditions and the relatively continous habitat along rivers. Triturus dobrogicus showed weak but significant genetic structure between tributaries of the three main river systems of Danube, Sava and Tisza. The highest genetic diversity was observed in the Sava drainage, suggesting that this area might have been a Pannonian refugium during the most recent glacial maximum. The relatively high level of genetic variation observed suggests that a genetic bottleneck during this period has not been extreme.
The Danube crested newt Triturus dobrogicus has been proposed to comprise two subspecies: T. d. dobrogicus and T. d. macrosoma. Uncertainty exists in the literature over their distribution and diagnosability. We conduct a multilocus phylogeographical survey and review published data to determine whether a two taxon treatment is warranted. Newly produced and published nuclear DNA data suggest intraspecific variation in the Pannonian Plain part of the range, but with extensive genetic admixture, whereas mitochondrial DNA data shows a lack of geographical structuring in T. dobrogicus altogether. None of the studied morphological characters suggest the presence of two geographical groups in T. dobrogicus unequivocally. Although Danube Delta newts do have relatively short bodies compared to the remainder of the range (the Pannonian and Lower Danube Plains and the Dnepr Delta), we argue that this finding can be explained by phenotypic plasticity – particularly in light of the incongruent evolutionary scenario suggested by genetic data. We conclude that the total body of evidence does not support the two subspecies hypothesis and recommend that T. dobrogicus is treated as a monotypic species.
In the recently published New Atlas of Amphibians and Reptiles of Europe (Sillero et al., 2014a), the distribution of the newt genus Triturus was not resolved at the level of the species. The main reason for this was the lack of high quality distribution data from in and around the parapatric contact zones between species, where interspecific hybridization occurs. We are working extensively on Triturus and the (particularly genetic) data we have accumulated allow us to map the individual Triturus species at the appropriate scale. We here provide a database composed of distribution data for the individual species, at generally high resolution, particularly from in and around contact zones. Based on this database we produce maps at the 50 × 50 km UTM grid resolution as used in the new atlas and highlight those grid cells in which more than one Triturus species occurs.
Many biodiversity hotspots are located in areas with a complex geological history, like Southeast Asia, where species diversity may still be far underestimated, especially in morphologically conservative groups like amphibians. Recent phylogenetic studies on the frog genus Leptobrachium from Southeast Asia revealed the presence of deeply divergent mitochondrial clades in Leptobrachium hendricksoni from Malaysia and Sumatra but populations from Thailand have not been studied so far. In this study, we re-evaluate patterns of intraspecific genetic diversity in L. hendricksoni based on the analysis of combined sequences of mitochondrial 12S and 16S genes (1310 base pairs) including for the first time samples from southern Thailand. Thai populations of L. hendricksoni formed a distinct clade with respect to populations from central and southern Malaysia and Sumatra. High sequence divergence between lineages from Thailand, Malaysia and Sumatra suggests the possible presence of cryptic species in L. hendricksoni. Divergence within L. hendricksoni dates back to the late Miocene, around 6 Mya, when lineages from Thailand, north Malaysia and Sumatra split from a lineage in south Malaysia, at about the same time as rising sea levels isolated the Thai-Malay peninsula. Subsequent splits took place later in the Pliocene, around 4.5 and 2.6 Mya. Our results highlight the role of geological history in promoting population divergence and speciation.
Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis associated with amphibian declines. Response and costs of infection varies greatly between species. Bd can induce a stress response in amphibians resulting in elevated corticosterone (CORT). We exposed Bombina variegata and Hyla arborea tadpoles to Bd+ or Bd- Salamandra salamandra larvae and measured CORT release rates, Bd infection loads, and survival through metamorphosis. Tadpoles of both species exposed to Bd+ larvae had elevated CORT release rates compared to tadpoles exposed to Bd- larvae. Bombina variegata appear less resistant to infection than H. arborea, showing higher Bd loads and more infected individuals. Within species, we did not find differences in cost of infection on survival, however more B. variegata tadpoles reached metamorphosis than H. arborea. The differences in resistance may be species specific, owing to higher immunity defenses with H. arborea having higher overall CORT release rates, and differences in antimicrobial peptides, or to differences in Bd strain or other unexplored mechanisms.
The last species list of the European herpetofauna was published by Speybroeck, Beukema and Crochet (2010). In the meantime, ongoing research led to numerous taxonomic changes, including the discovery of new species-level lineages as well as reclassifications at genus level, requiring significant changes to this list. As of 2019, a new Taxonomic Committee was established as an official entity within the European Herpetological Society, Societas Europaea Herpetologica (SEH). Twelve members from nine European countries reviewed, discussed and voted on recent taxonomic research on a case-by-case basis. Accepted changes led to critical compilation of a new species list, which is hereby presented and discussed. According to our list, 301 species (95 amphibians, 15 chelonians, including six species of sea turtles, and 191 squamates) occur within our expanded geographical definition of Europe. The list includes 14 non-native species (three amphibians, one chelonian, and ten squamates).