Underground environments are increasingly recognised as important habitats for the distribution of certain amphibians. However, very few analyses tested whether amphibians occur randomly in underground environments, or they select cavities with specific environmental features. We assessed the distribution of the cave salamander Hydromantes (Speleomantes) strinatii in an area of NW Italy during summer, and analysed relationships between salamander distribution and multiple cave features, considering parameters describing both the biotic and the abiotic environment. Using visual encounter surveys, species’ detection probability was high, indicating that this technique provides reliable information on distribution. Salamanders were associated to caves with cold and humid microclimate, presence of wet walls, and hosting large numbers of Meta spiders. The association with less luminous caves was close to significance. Distribution data were not affected by spatial autocorrelation, suggesting that cave features are more important than the proximity to other occupied caves in determining the pattern of occupancy. Caves are heterogeneous environments: cave salamanders are strongly related to the features of underground environments. Food availability and abiotic features are major determinants of suitability for cave salamanders. Inter-correlation among biotic and abiotic cave features makes it complex identifying the role of factors determining species distribution, but quantitative analyses and PCA help to unravel the cave habitat requirements for amphibians.
In the last decade, eDNA and metabarcoding have opened new avenues to biodiversity studies; amphibians and reptiles are animals for which these new approaches have allowed great leaps forward. Here we review different approaches through which eDNA can be used to study amphibians, reptiles and many more organisms. eDNA is often used to evaluate the presence of target species in freshwaters; it has been particularly useful to detect invasive alien amphibians and secretive or rare species, but the metabarcoding approach is increasingly used as a cost-effective approach to assess entire communities. There is growing evidence that eDNA can be also useful to study terrestrial organisms, to evaluate the relative abundance of species, and to detect reptiles. Metabarcoding has also revolutionized studies on the microbiome associated to skin and gut, clarifying the complex relationships between pathogens, microbial diversity and environmental variation. We also identify additional aspects that have received limited attention so far, but can greatly benefit from innovative applications of eDNA, such as the study of past biodiversity, diet analysis and the reconstruction of trophic interactions. Despite impressive potential, eDNA and metabarcoding also bear substantial technical and analytical complexity; we identify laboratory and analytical strategies that can improve the robustness of results. Collaboration among field biologists, ecologist, molecular biologists, and bioinformaticians is allowing fast technical and conceptual advances; multidisciplinary studies involving eDNA analyses will greatly improve our understanding of the complex relationships between organisms, and our effectiveness in assessing and preventing the impact of human activities.
Understanding the relationship between environmental features and species
distribution is a key step for successful habitat conservation. In
semiaquatic amphibians, the features of both breeding sites and the
surrounding upland habitat can play important roles. We evaluated the
relative role of (1) stream morphology, (2) biotic features of water, and
(3) composition of landscape surrounding wetlands, for the distribution of
the fire salamander, Salamandra salamandra. We determined the presence of
larvae in 132 localities, and we used an information-theoretic approach to
build species distribution models. We then used variance partitioning to
evaluate the relative importance of environmental variables. A model
including both stream and landscape features explained a large proportion of
variation. Larvae were associated to heterogeneous and shallow streams, with
scarce periphyton, rich macrobenthos communities characteristic of
oligotrophic water, and surrounded by woodlands. Variance partitioning
showed that stream morphology was the parameter with the largest independent
effect, but most of variation was explained by the combined effect of
multiple variables, suggesting a strong interplay among biotic and abiotic
features in determining species distribution. The complementation between
multiple elements, such as wetlands and landscape features, can be the key
of a correct understanding of distribution of semi-aquatic amphibians.
A precise knowledge of the spatial distribution of taxa is essential for decision-making processes in land management and biodiversity conservation, both for present and under future global change scenarios. This is a key base for several scientific disciplines (e.g. macro-ecology, biogeography, evolutionary biology, spatial planning, or environmental impact assessment) that rely on species distribution maps. An atlas summarizing the distribution of European amphibians and reptiles with 50 × 50 km resolution maps based on ca. 85 000 grid records was published by the Societas Europaea Herpetologica (SEH) in 1997. Since then, more detailed species distribution maps covering large parts of Europe became available, while taxonomic progress has led to a plethora of taxonomic changes including new species descriptions. To account for these progresses, we compiled information from different data sources: published in books and websites, ongoing national atlases, personal data kindly provided to the SEH, the 1997 European Atlas, and the Global Biodiversity Information Facility (GBIF). Databases were homogenised, deleting all information except species names and coordinates, projected to the same coordinate system (WGS84) and transformed into a 50 × 50 km grid. The newly compiled database comprises more than 384 000 grid and locality records distributed across 40 countries. We calculated species richness maps as well as maps of Corrected Weighted Endemism and defined species distribution types (i.e. groups of species with similar distribution patterns) by hierarchical cluster analysis using Jaccard’s index as association measure. Our analysis serves as a preliminary step towards an interactive, dynamic and online distributed database system (NA2RE system) of the current spatial distribution of European amphibians and reptiles. The NA2RE system will serve as well to monitor potential temporal changes in their distributions. Grid maps of all species are made available along with this paper as a tool for decision-making and conservation-related studies and actions. We also identify taxonomic and geographic gaps of knowledge that need to be filled, and we highlight the need to add temporal and altitudinal data for all records, to allow tracking potential species distribution changes as well as detailed modelling of the impacts of land use and climate change on European amphibians and reptiles.