Predation is one of the main selective forces in nature, frequently selecting potential prey for developing escape strategies. Escape ability is typically influenced by several morphological parameters, such as morphology of the locomotor appendices, muscular capacity, body mass, or fluctuating asymmetry, and may differ between sexes and age classes. In this study, we tested the relationship among these variables and jumping performance in 712 Iberian green frogs Pelophylax perezi from an urban population. The results suggest that the main determinant of jumping capacity was body size (explaining 48% of variance). Larger frogs jumped farther, but jumping performance reached an asymptote for the largest frogs. Once controlled by structural body size, the heaviest frogs jumped shorter distances, suggesting a trade-off between fat storage and jumping performance. Relative hind limb length also determined a small but significant percentage of variance (2.4%) in jumping performance—that is, the longer the hind limbs, the greater the jumping capacity. Juveniles had relatively shorter and less muscular hind limbs than adults (for a given body size), and their jumping performance was poorer. In our study population, the hind limbs of the frogs were very symmetrical, and we found no effect of fluctuating asymmetry on jumping performance. Therefore, our study provides evidence that jumping performance in frogs is not only affected by body size, but also by body mass and hind limb length, and differ between age classes.

The influence of aquatic and riparian habitats on the composition of the local herpetofauna has not been studied extensively. We used redundancy analysis and multivariate ordination methods to evaluate the occurrence of semi‐aquatic reptiles in south‐eastern France, the Iberian Peninsula, and Morocco where the climate transitions from humid temperate to subtropical desert. All the semi‐aquatic reptile species present in this region were studied, including two native turtles (Emys orbicularis and Mauremys leprosa), three native snakes (Natrix astreptophora, N. helvetica, and N. maura), and one introduced turtle (Trachemys scripta). We hypothesized that these species will vary in their responses to differences in the composition of riparian habitats (vegetative community and relative proportion of trees, shrubs, grasses, water and bare ground surface) along the aridity gradient in the region. We found that the habitat niche marginality and niche breadth varied widely across species and climatic regions, although most of the species display a greater habitat niche breadth in the transitional semi‐arid belt. Mauremys leprosa and N. maura were the more generalist species, occupying a wide range of freshwater habitats, including streams associated with impoverished vegetation communities, characteristic of the arid southern Mediterranean region.

BackgroundCongeneric species of reptiles frequently exhibit partitioning in terms of their use of habitats or trophic resources in order to reduce competition. In this study, we investigated habitat use by two species of European skinks: Chalcides bedriagai and Chalcides striatus, based on 49 records from southern France, Spain, and Portugal.MethodsWe measured three levels of niche descriptors: macroscale (climate, topography, and substrate), mesoscale (plant associations), and microscale (vegetation cover and shelters). We assessed the associations between these environmental descriptors and the occurrence of the skinks.ResultsOur results showed that the two species occupied opposite extremes of the ecological gradient i.e., C. bedriagai in semi-arid environments and C. striatus in temperate-oceanic environments, but there was broad ecological overlap in transitional climates at all of the habitat scales examined. This overlap was demonstrated by the presence of syntopy in geographically distant sites with different environmental characteristics.DiscussionThe morphological differences between the two species, and possibly their different use of microhabitats, might favor this mesoscale overlap between congeneric species, which is relatively unusual in Mediterranean lizards.

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