Phylogeography of Sardinian Cave Salamanders (Genus Hydromantes) Is Mainly Determined by Geomorphology

Detecting the factors that determine the interruption of gene flow between populations is key to understanding how speciation occurs. In this context, caves are an excellent system for studying processes of colonization, differentiation and speciation, since they represent discrete geographical units often with known geological histories. Here, we asked whether discontinuous calcareous areas and cave systems represent major barriers to gene flow within and among the five species of Sardinian cave salamanders (genus Hydromantes) and whether intraspecific genetic structure parallels geographic distance within and among caves. We generated mitochondrial cytochrome b gene sequences from 184 individuals representing 48 populations, and used a Bayesian phylogeographic approach to infer possible areas of cladogenesis for these species and reconstruct historical and current dispersal routes among distinct populations. Our results show deep genetic divergence within and among all Sardinian cave salamander species, which can mostly be attributed to the effects of mountains and discontinuities in major calcareous areas and cave systems acting as barriers to gene flow. While these salamander species can also occur outside caves, our results indicate that there is a very poor dispersal of these species between separate cave systems

Geographic Variation in Advertisement Calls in a Tree Frog Species: Gene Flow and Selection Hypotheses

In a species with a large distribution relative to its dispersal capacity, geographic variation in traits may be explained by gene flow, selection, or the combined effects of both. Studies of genetic diversity using neutral molecular markers show that patterns of isolation by distance (IBD) or barrier effect may be evident for geographic variation at the molecular level in amphibian species. However, selective factors such as habitat, predator, or interspecific interactions may be critical for geographic variation in sexual traits. We studied geographic variation in advertisement calls in the tree frog Hyla japonica to understand patterns of variation in these traits across Korea and provide clues about the underlying forces for variation.We recorded calls of H. japonica in three breeding seasons from 17 localities including localities in remote Jeju Island. Call characters analyzed were note repetition rate (NRR), note duration (ND), and dominant frequency (DF), along with snout-to-vent length.The findings of a barrier effect on DF and a longitudinal variation in NRR seemed to suggest that an open sea between the mainland and Jeju Island and mountain ranges dominated by the north-south Taebaek Mountains were related to geographic variation in call characters. Furthermore, there was a pattern of IBD in mitochondrial DNA sequences. However, no comparable pattern of IBD was found between geographic distance and call characters. We also failed to detect any effects of habitat or interspecific interaction on call characters.Geographic variations in call characters as well as mitochondrial DNA sequences were largely stratified by geographic factors such as distance and barriers in Korean populations of H. japonica. Although we did not detect effects of habitat or interspecific interaction, some other selective factors such as sexual selection might still be operating on call characters in conjunction with restricted gene flow

Grey squirrels in central Italy: a new threat for endemic red squirrel subspecies

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Extending the natural range of a declining species : Genetic evidence that great crested newt (Triturus cristatus) populations in the Scottish highlands are native

Determining whether isolated populations of a species are native or introduced is important for conservation, as non-native occurrences are likely to be of lower priority for conservation organisations with limited resources. The great crested newt Triturus cristatus is an important wetland flagship species in the UK, and recent evidence suggested that putatively introduced isolated occurrences around Inverness (Scottish Highlands) might be of native origin. Here, we use six microsatellite loci and mtDNA sequence information (ND4 region) to genetically characterise eight Highland populations, comparing them with two populations from central Scotland (the northern limit of the species’ continuous UK distribution) and central England (Leicestershire). Highland populations were characterised by low amounts of genetic variation at high degrees of differentiation, which can be best interpreted by demographic instability and isolation at the periphery of the species’ range. We found no evidence for population bottlenecks in the last decades. All studied individuals possessed a single mtDNA haplotype previously described for British T. cristatus. Taken together, these results suggest that T. cristatus is native to the Scottish Highlands, with important implications for its local conservation status