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

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

Making more with standard ecotoxicological tests: Using sets of behavioural markers to test the effect of endosulfan on amphibian tadpoles

peer reviewe

Teratogenic potential of nanoencapsulated vitamin A evaluated on an alternative model organism, the tunicate Ciona intestinalis

Nano-encapsulation is a technology used to pack substances in order to enhance their stability and bioavailability, but this packing may interact with living systems, causing unexpected toxicity. Vitamin A (vit A) is a substance that has received attention, because in developed countries, the increasing availability of supplements is leading to its excessive intake. This study aims to compare teratogenic effects caused by exposure to the traditional formulation of vit A versus nano-encapsulated vit A. We used ascidian embryos as an alternative model. Ascidians are marine organisms closely related to vertebrates that share with them a body plan and developmental programme, including the morphogenetic role of retinoic acid (RA). Our data showed that the adverse effects of exposure to the same concentration of the two formulations were different, suggesting that the nano-encapsulation increased the bioavailability of the molecule, which could be better absorbed and metabolised to RA, the effective teratogenic substance

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

Environmental factors determining growth of salamander larvae : a field study

Larval growth and survival of organisms are strongly influenced by abiotic and biotic factors, as demonstrated by experimental studies performed under controlled laboratory or semi-natural conditions. Even if they have many advantages, experiments cannot cover the full complexity of natural conditions and field studies are needed for a better understanding of how environmental variation determines growth and development rate. Fire salamander Salamandra salamandra females give birth to larvae in a variety of habitats, both epigean and subterranean. In caves, salamander larvae successfully grow and metamorphose, but their growth is more than three times longer than in epigean streams and factors determining these differences require investigation. We performed a field study to understand the factors related to the growth of fire salamander larvae in different environmental conditions, evaluating the relationship between environmental features and larval growth and differences between caves and epigean spring habitats. Both caves and epigean larvae successfully grew. Capture-mark-recapture allowed to individually track individuals along their whole development, and measure their performance. Growth rate was significantly affected by environmental variables: larvae grew faster in environments with abundant invertebrates and few conspecifics. Taking into account the effect of environmental variables, larval growth was significantly lower in caves. Food availability plays a different effect in the two environments. Larval growth was positively related to the availability of invertebrates in epigean sites only. The development rate of hypogeous populations of salamanders is slower because of multiple parameters, but biotic factors play a much stronger role than the abiotic ones

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