Temporal variability of spawning site selection in the frog Rana dalmatina: consequences for habitat management

We evaluated whether R. dalmatina females laid their eggs randomly within a pond or preferred particular microhabitats. The same measures were performed in the same area in two consecutive years to determine whether the pattern remained constant over time. In 2003, we observed a significant selection for areas with more submerged deadwood and vegetation, presence of emergent ground and low water depth. However, these results were not confirmed in the subsequent year when none of the microhabitat features measured had a significant effect. Although microhabitat features can strongly influence tadpoles, the temporal variability of habitat at this spatial scale suggests that habitat management could be more effective if focused on a a wider spatial scale

Variabilidad temporal en la elección de los lugares de freza de la rana ágil Rana dalmantina: consecuencias para la gestión del hábitat

We evaluated whether R. dalmatina females laid their eggs randomly within a pond or preferred particular microhabitats. The same measures were performed in the same area in two consecutive years to determine whether the pattern remained constant over time. In 2003, we observed a significant selection for areas with more submerged deadwood and vegetation, presence of emergent ground and low water depth. However, these results were not confirmed in the subsequent year when none of the microhabitat features measured had a significant effect. Although microhabitat features can strongly influence tadpoles, the temporal variability of habitat at this spatial scale suggests that habitat management could be more effective if focused on a a wider spatial scale.Evaluamos si las hembras de R. dalmantina ponían sus huevos al azar en una charca o preferían microhábitats particulares. Durante dos años consecutivos se realizaron las mismas mediciones en la misma área, para determinar si el patrón era constante a través del tiempo. En el año 2003 observamos una selección significativa de áreas con mayor cantidad de ramas muertas y otra vegetación sumergidas, con zonas del fondo emergentes y aguas más someras. Sin embargo, estos resultados no fueron confirmados al año siguiente, en el cual ninguna de las características del microhábitat medidas tuvo un efecto significativo. A pesar de que las características del microhábitat pueden tener gran influencia sobre los renacuajos, la variabilidad temporal del hábitat a esta escala espacial sugiere que la gestión del hábitat podría ser más efectiva si fuera proyectada según una escala espacial mayor

The Racovitzan impediment and the hidden biodiversity of unexplored environments

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cost-effective spatial sampling designs for field surveys of species distribution

High-quality biodiversity inventories are key tools to develop effective conservation strategies, but financial resources devoted to systematic species inventories are usually limited. Different sampling strategies have been proposed to efficiently allocate such limited resources (i.e. accessibility-based, stratified random and grid samplings), but their effectiveness may depend on the aim of the survey. Our aim was to assess which approach can provide the best trade-off between sampling costs and accuracy in estimating both single species distribution and species set composition. We generated simulated species distribution data to compare costs and performances of the three sampling methods in assessing species distribution. When we aim at measuring species range (i.e. area of occupancy or extent of occurrence), or obtaining baseline ecological data for conservation assessments (i.e. niche breadth), grid sampling usually provided the best trade-off between performance and costs at both the single- and multi-species levels. Otherwise, the stratified random sampling outperformed the other methods when we are interested in assessing the relative rarity (i.e. species frequency) of the species across the study area. Low quality distribution data can lead to heavily biased conclusions on biodiversity trends or impacts of environmental changes; our findings highlight that selecting the right sampling strategy is essential to obtain reliable estimates of both single species distribution and species set composition

TetraDENSITY. A database of population density estimates in terrestrial vertebrates

Motivation: Population density is a key demographic parameter influencing many ecological processes, and macroecology has described both intra- and interspecific patterns of variation. Population density data are expensive to collect and contain many forms of noise and potential bias; these factors have impeded investigation of macroecological patterns, and many hypotheses remain largely unexplored. Population density also represents fundamental information for conservation, because it underlies population dynamics and, ultimately, extinction risk. Here we present TetraDENSITY, an extensive dataset with > 18,000 records of density estimates for terrestrial vertebrates, in order to facilitate new research on this topic. Main types of variable contained: The dataset includes taxonomic information on species, population density estimate, year of data collection, season, coordinates of the locality, locality name, habitat, sampling method and sampling area. Spatial location and grain: Global. Spatial accuracy varies across studies; conservatively, it can be considered at 1°, but for many data it is much finer. Time period and grain: From 1926 to 2017. Temporal accuracy is yearly in most cases, but studies with higher temporal resolution (season, month) are also present. Major taxa and level of measurement: Amphibians in terrestrial phase, reptiles, birds and mammals. Estimates derive from multiple methods, reflecting the study taxon, location and techniques available at the time of density estimation

Habitat availability for amphibians and extinction threat: A global analysis

Aim: Habitat loss and degradation are the factors threatening the largest number of amphibian species. However, quantitative measures of habitat availability only exist for a small subset of them. We evaluated the relationships between habitat availability, extinction risk and drivers of threat for the world's amphibians. We developed deductive habitat suitability models to estimate the extent of suitable habitat and the proportion of suitable habitat (PSH) inside the geographic range of each species, covering species and areas for which little or no high-resolution distribution data are available. Location: Global. Methods: We used information on habitat preferences to develop habitat suitability models at 300-m resolution, by integrating range maps with land cover and elevation. Model performance was assessed by comparing model output with point localities where species were recorded. We then used habitat availability as a surrogate of area of occupancy. Using the IUCN criteria, we identified species having narrow area of occupancy, for which extinction risk is likely underestimated. Results: We developed models for 5363 amphibians. Validation success of models was high (94%), being better for forest specialists and generalists than for open habitat specialists. Generalists had proportionally more habitat than forest or open habitat specialists. The PSH was lower for species having small geographical ranges, currently listed as threatened, and for which habitat loss is recognized as a threat. Differences in habitat availability among biogeographical realms were strong. We identified 61 forest species for which the extinction risk may be higher that currently assessed in the Red List, due to limited extent of suitable habitat. Main conclusions: Habitat models can accurately predict amphibian distribution at fine scale and allow describing biogeographical patterns of habitat availability. The strong relationship between amount of suitable habitat and extinction threat may help the conservation assessment in species for which limited information is currently available

Same diet, different strategies : variability of individual feeding habits across three populations of Ambrosi’s cave salamander (Hydromantes ambrosii)

European cave salamanders of the genus Hydromantes are a group of eight species endemic to Italy and south-eastern France. Knowledge on the trophic niche of European Hydromantes is poor, and the few available studies only partially investigate their feeding habits. We performed an indepth study on the trophic niche of the Ambrosi's cave salamander (H. ambrosii), assessing the potential divergences among three different populations. All the populations had a similar diet composition, showing a wider trophic niche in fall compared to spring. In only one population, "true specialists" were present; however, in all three populations, generalist individuals always represented the larger proportion. Interspecific and intraspecific competition did not play an important role in determining individual dietary specialisation in H. ambrosii; contrarily, the characteristics of the surrounding environment seemed to be an important factor. The best body conditions were observed in the population located in the site where the non-arboreal vegetation cover was the highest. Besides providing new information on the trophic niche of H. ambrosii, we here showed that studies encompassing both intrinsic and extrinsic factors at the population level are needed to fully understand the trophic dynamics occurring among European cave salamanders

Global patterns of β-diversity along the phylogenetic time-scale : the role of climate and plate tectonics

Aim: We aimed to assess the relative influence of the historical and contemporary processes determining global patterns of current \u3b2-diversity. Specifically, we quantified the relative effects of contemporary climate and historical plate tectonics on \u3b2-diversity at different phylogenetic scales. Location: Global. Time Period: Contemporaneous. Major taxa studied: Mammals and birds. Methods: We analysed the current \u3b2-diversity patterns of birds and mammal assemblages at sequential depths in the phylogeny, that is, from the tips to deeper branches. This was done by slicing bird and mammal phylogenetic trees into 66 time slices of 1 Ma (from 0 to 65 Ma) and recording the branches within each slice. Using global distribution data, we defined the branches\u2019 geographical distribution as the union of the corresponding downstream species distributions. For each time slice, we (a) computed pairwise \u3b2-diversity across all the grid cells for the whole world and (b) estimated the correlation between this \u3b2-diversity matrix and contemporary climatic and geographical distances, and past geological distances, a proxy for plate tectonics. Results: Contemporary climate best explained the \u3b2-diversity of shallow branches (i.e., species). For mammals, the geographical isolation of landmasses generated by plate tectonics best explained the \u3b2-diversity of deeper branches, whereas the effect of past isolation was weaker for birds. Main conclusions: Our study shows that the relative influence of contemporary climate and plate tectonics on the \u3b2-diversity of bird and mammal assemblages varies along the phylogenetic time-scale. Our phylogenetic time-scale approach is general and flexible enough to be applied to a broad spectrum of study systems and spatial scales

Growing in the darkness: predation ability and cannibalism in cave-born larvae of fire salamander, Salamandra salamandra (Linnaeus, 1758)

Crescere al buio: abilit\ue0 predatoria e cannibalismo in larve di salamandra pezzata, Salamandra salamandra nate in grotta. La salamandra pezzata in diverse aree carsiche del proprio areale pu\uf2 deporre le larve anche in ambienti ipogei come grotte naturali e artificiali. Lo scopo di questo studio \ue8 valutare se le popolazioni che utilizzano tali, inusuali, siti riproduttivi, abbiano sviluppato degli adattamenti specifici. Per tale scopo abbiamo effettuato alcuni esperimenti comportamentali sulla capacit\ue0 di predazione e sul cannibalismo. Da 20 grotte e da 20 ruscelli adiacenti abbiamo raccolto delle larve che abbiamo allevato in due differenti condizioni: in ambiente ipogeo ed in ambiente epigeo. Sia le larve da grotta che da ruscello sono state in grado di catturare prede in condizioni di buio totale. Le larve nate in grotta hanno per\uf2 mostrato una maggiore efficienza. Per quanto riguarda il cannibalismo esso \ue8 ridotto alla nascita e molto pi\uf9 accentuato dopo un mese di vita delle larve. Il grado di digiuno e la taglia delle larve influenzano l\u2019aggressivit\ue0. Non sono per\uf2 risultati evidenti effetti della provenienza delle larve o delle condizioni di allevamento

Estimating abundance and habitat suitability in a micro-endemic snake: the Walser viper

Recently described species suffer lack of information that hampers setting up appropriate conservation strategies. The situation is particularly complex with micro-endemic snakes, for which detection and monitoring are particularly challenging. The Walser viper Vipera walser is a recently described snake inhabiting a small area of the SW Italian alps. We combined information on species distribution with repeated monitoring to identify the areas most suitable for the species, and to obtain estimates of species abundance. Species distribution models were used to identify the topographical, climatic, and land-cover features related to the occurrence of vipers. Furthermore, repeated transects and N-mixture models were used to estimate abundance and to identify factors related to the variation of abundance. The available data suggested that the species has a disjunct range, with a Northern range of ~45 km2 , and a southern range of ~225 km2. Distribution models suggested that vipers are associated with areas with open egetation,altitude between 1300 and 2300 m, high precipitation, low forest cover, low slope, and southern aspect. N-mixture models confirmed very low detection probability of these vipers, and suggested that the species has a low abundance,with the highest abundance in south-facing plots. We provide the first quantitative information on habitats and abundance variation for Walser vipers. The broad confidence intervals of abundance estimates exemplify the complexity of providing range-wide measures of abundance for secretive species. Given the narrow range of these vipers, continuous monitoring is required to understand how they respond to ongoing environmental changes in mountainous areas