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  • Author or Editor: Neftalí Sillero x
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Abstract

New records of the frog Hyla meridionalis have been reported on the Iberian Central mountain range, although it is not clear if those records correspond to an expansion process or to a lack of sampling. The species' global distribution was modelled to identify possible areas of expansion in the current environment and in a near future environment. To verify the effects of modelling a dynamic situation, the hypothetical expansion process from south to north was simulated in the current scenario. The species records were partitioned in four different datasets and modelled iteratively over a study area enclosing all records: records only from North Africa, from North Africa and South Iberian Peninsula, from North Africa and all the Iberian Peninsula, and from the entire distribution. The complete dataset was also used to extrapolate the model to a current and future global environmental scenarios. The models were compared by subtraction per pairs and by Cohen's Kappa. No spatio-temporal trends were detected in species records; therefore, the hypothesis of a recent expansion is nor supported. The species spread only to the Mediterranean part of the Iberian Peninsula when modelling only with African records, and to Europe when modelling also with Iberian records. The extrapolation models were moderately similar: large suitable areas were predicted in all the continents. Temperature variables contributed more to models. The species can expand to new suitable areas, although it is not possible to know if it would expand outside the biogeographical regions where the species is present.

In: Amphibia-Reptilia

Abstract

Road-kills are the greatest source of direct human-induced wildlife mortality, especially in amphibians. Country roads could act as the most important source of mortality when main roads act as strong barriers hampering the migration movements of some species. Mortality patterns of amphibians on country roads (1380 km) were studied in Salamanca (Spain) in order to quantify the mortality levels, to test the effects of sex and age factors on road-kills, to determine the spatial distribution patterns of road-kills, and to identify routes of migration through a friction map and hotspots of road-kills. From a total of 819 records of amphibians, 38.1% were road-killed and 61.9% were live. Fourteen amphibian species were recorded during the surveys (10 anurans and four urodeles). The species more affected by road-kills were the anurans Bufo calamita, Pelobates cultripes and B. bufo (38.5, 23.4 and 11.9%, respectively). Females had higher incidence of road-kills than males, due to the differential activity patterns of both sexes during the reproductive period. Adults were the most common age period and also the most road-killed. The spatial distribution patterns of live and road-killed records were clustered. On the sampled roads, there were 0.23 road-kills per kilometre and 52 hotspots of road-kills. The friction map showed that most of the road-killed and live specimens were located on migration routes crossing suitable habitats. Conservation measures should be implemented in these areas, as these mortality patterns may be causing significant negative impacts at the population level.

In: Amphibia-Reptilia

Animal mortality caused by vehicle collisions is one of the main ecological impacts of roads. Amphibians are the most affected group and road fatalities have a significant impact on population dynamics and viability. Several studies on Iberian amphibians have shown the importance of country roads on amphibian road mortality, but still, little is known about the situation in northern Portugal. By being more permeable to amphibian passage, country roads represent a greater source of mortality than highways, which act as barriers. Thus, mitigation measures should be applied, but due to the extensive road network, the identification of precise locations (hotspots) and variables related to animal-vehicle collision is needed to plan these measures successfully. The aim of the study was to analyse the spatial occurrence and related factors linked to amphibian mortality on a number of country roads in northern Portugal, using spatial statistics implemented in GIS and applying a binary logistical regression. We surveyed 631 km of road corresponding to seven transects, and observed 404 individual amphibians: 74 (18.3%) alive and 330 (81.7%) road-killed. Bufo bufo represented 80% of the mortality records. Three transects showed clustered distribution of road-kills, and broadleaved forests and road ditches were the most important factors associated with hotspots of road-kill. Logistic regression models showed that habitat quality, Bufo bufo’s habitat preferences, and road ditches are positively associated with amphibians’ road mortality in northern Portugal, whereas average altitude and length of walls were negatively associated. This study is a useful tool to understand spatial occurrence of amphibian road-kills in the face of applying mitigation measures on country roads from northern Portugal. This study also considers the necessity of assessing the condition of amphibian local populations to understand their road-kills spatial patterns and the urgency to apply mitigation measures on country roads.

In: Amphibia-Reptilia

In the recently published New Atlas of Amphibians and Reptiles of Europe (Sillero et al., 2014a), the distribution of the newt genus Triturus was not resolved at the level of the species. The main reason for this was the lack of high quality distribution data from in and around the parapatric contact zones between species, where interspecific hybridization occurs. We are working extensively on Triturus and the (particularly genetic) data we have accumulated allow us to map the individual Triturus species at the appropriate scale. We here provide a database composed of distribution data for the individual species, at generally high resolution, particularly from in and around contact zones. Based on this database we produce maps at the 50 × 50 km UTM grid resolution as used in the new atlas and highlight those grid cells in which more than one Triturus species occurs.

In: Amphibia-Reptilia

Abstract

Altitude is an important factor when explaining species distributions. However, many biogeographical studies register altitude directly through topographic maps; a time-consuming manual process prone to mistakes. Currently, GIS and DEMs allow this work to be done more efficiently. Two methods for registering altitude for locations of amphibians and reptiles in the Iberian Peninsula were compared in order to evaluate their efficiency and similarity: manually through topographic maps, and automatically with a GIS, where two DEMs were analysed: the SRTM DEM and a DEM generated through topographic maps. The SRTM altitudes were similar to those recorded by the manual method (only Rana perezi presented differences), whereas the other DEM had differences in almost all amphibians and three reptiles. The differences between both DEMs corresponded mostly to rivers and band effect of radar sensor. The GIS method was faster, efficient and no time was consumed in searching and correcting human errors.

In: Amphibia-Reptilia

Abstract

The ‘smooth newt’, the taxon traditionally referred to as Lissotriton vulgaris, consists of multiple morphologically distinct taxa. Given the uncertainty concerning the validity and rank of these taxa, L. vulgaris sensu lato has often been treated as a single, polytypic species. A recent study, driven by genetic data, proposed to recognize five species, L. graecus, L. kosswigi, L. lantzi, L. schmidtleri and a more restricted L. vulgaris. The Carpathian newt L. montandoni was confirmed to be a closely related sister species. We propose to refer to this collective of six Lissotriton species as the smooth newt or Lissotriton vulgaris species complex. Guided by comprehensive genomic data from throughout the range of the smooth newt species complex we 1) delineate the distribution ranges, 2) provide a distribution database, and 3) produce distribution maps according to the format of the New Atlas of Amphibians and Reptiles of Europe, for the six constituent species. This allows us to 4) highlight regions where more research is needed to determine the position of contact zones.

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In: Amphibia-Reptilia