Speleomantes

Abstract: Aim To infer the phylogenetic relationships and biogeography of Hydromantes, with special emphasis on the European taxa. In particular, we aimed to test: (1) the monophyly of the European species and current views on their interrelationships; and (2) previously proposed timings of the separation of European and American Hydromantes, and of biogeographically important events within Europe. Location California and the Western Mediterranean Basin, specifically southeast France, Italy, and the island of Sardinia. Methods Partial sequences of mitochondrial genes (cytochrome b and 12S rRNA) were obtained from 45 specimens of Hydromantes, including all European extant species and subspecies, and two species from California. In addition, a fragment of the mitochondrial 16S rRNA gene was amplified for 16 specimens. Data sets were aligned using ClustalX, and well-supported phylogenetic trees were produced using maximum-likelihood, Bayesian and maximum-parsimony methods. Estimates of divergence times were obtained with the program r8s, the molecular clock being calibrated using the opening of the Strait of Gibraltar, the final event in the Messinian Salinity Crisis of 5.3 Ma. Results Separation between the American and European clades occurred approximately 13.5 Ma, most probably before or after westward dispersal across the Bering Land Bridge. In Europe, divergence started in the late Miocene, when Hydromantes (A.) genei separated from other members of the genus 9 Ma and colonized south-west Sardinia. Movement between the European mainland and Sardinia, by a member of the subgenus Speleomantes, occurred in the Messinian Salinity Crisis, after the Mediterranean Basin desiccated almost completely 5.96 Ma. Subsequent widespread aridification fragmented the geographical ranges of Hydromantes, which live in cool and humid conditions, resulting in the origin of the six species in the subgenus Speleomantes. In contrast, a second period of diversification, in continental Europe 2‐1.3 Ma, was probably caused by very cold interludes during the climatic oscillations that characterized the Pleistocene. Main conclusions The molecular clock used here indicates that the separation of Californian and European Hydromantes occurred more recently than previously believed, and the same is true of some subsequent phylogenetic divergences within Europe. Estimated dates for these divergence events are consistent with known geophysical and climatic events that could have caused or facilitated them.

Abstract: Trophic niche may be the most important ecological dimension for some vertebrate groups and in particular for terrestrial amphibians, that are important predators of soil invertebrates. In general, resource partitioning occurs between syntopic species with similar ecological niches, and coexistence patterns seem to be regulated by temporal resource variability. However most of the generalization on foraging strategies of terrestrial salamanders are extrapolated from studies on New World temperate species, thus we investigated the seasonal effect of resource variation in an European forest ecosystem, in which two ecologically similar but phylogenetically distinct salamander species are found. The diet of adult and juvenile cave salamanders (Speleomantes strinati), and of adult spectacled salamander (Salamandrina perspicillata) was obtained by stomach flushing, and results showed large seasonal changes both in prey availability and in salamander realised trophic niche. Values of trophic diversity were similar and niche overlaps were large among all salamander groups in spring, during high prey availability. Conversely in autumn, when a two-fold reduction in prey biomass was observed, there was a clear niche partitioning as the smaller S. perspicillata shifted from a generalist to a specialized trophic strategy. Juvenile Speleomantes strinatii, that largely overlapped in size with S. perspicillata, did not show any change in diet, suggesting that the feeding strategies were species-specific and not size-mediated. The observed patterns of variation in feeding ecology indicate that similar predators may react differently to changing prey availability to enhance niche partitioning. We also observed an increased energy intake during autumn for S perspicillata and S. strinatii juveniles, possibly related to differences in microhabitat use and activity patterns.

Abstract: North America and the neotropics harbor nearly all species of plethodontid salamanders. In contrast, this family of caudate amphibians is represented in Europe and Asia by two genera, Speleomantes and Karsenia, which are confined to small geographic ranges. Compared to neotropical and North American plethodontids, mortality attributed to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) has not been reported for European plethodontids, despite the established presence of Bd in their geographic distribution. We determined the extent to which Bd is present in populations of all eight species of European Speleomantes and show that Bd was undetectable in 921 skin swabs. We then compared the susceptibility of one of these species, Speleomantes strinatii, to experimental infection with a highly virulent isolate of Bd (BdGPL), and compared this to the susceptible species Alytes muletensis. Whereas the inoculated A. muletensis developed increasing Bd-loads over a 4-week period, none of five exposed S. strinatii were colonized by Bd beyond 2 weeks post inoculation. Finally, we determined the extent to which skin secretions of Speleomantes species are capable of killing Bd. Skin secretions of seven Speleomantes species showed pronounced killing activity against Bd over 24 hours. In conclusion, the absence of Bd in Speleomantes combined with resistance to experimental chytridiomycosis and highly efficient skin defenses indicate that the genus Speleomantes is a taxon unlikely to decline due to Bd.

Abstract: Recently published research addressing the question of relationships and biogeography of European plethodontid salamanders has refined time estimates for divergence from American relatives. The recently discovered Korean plethodontid Karsenia is either the sister-taxon of Hydromantes (which has members in Europe and California), or a close relative and co-member of a larger clade that originated in western North America, not eastern North America as formerly thought. The new information strengthens the biogeographical hypothesis that Hydromantes entered Eurasia via the Bering Land Bridge. Arguments are made favoring the placement of European and American relatives in a genus Hydromantes, with an American clade (subgenus Hydromantes) and a European clade (subgenera Atylodes and Speleomantes).