La comunidad Herpetológica de Caurel: Biogeografía y Ecología

Abstract

AbstractThe present work studies the herpetological community of Caurel (NW, of Spain): biogeography and ecology. Biogeography: altitudinal distribution of species, altitudinal variation in abundance of species and stratification reflect a decrease with the altitude bound to climatic reasons and productivity in Reptiles and to lesser heterogeneity of biotopes in Amphibians. There is a greater altitudinal stratification of the subcommunity of Amphibians than of Reptiles. Ecology: the different physiological requirements of Amphibians from land habitats and Lizards are reflected in a temporal alternation (seasonal and daily) in the exploitation of the same trophical resource. The snakes occupy another trophical level (predators and superpredators) and the tritons live in another habitat (subaquatic) with different resources and they have a different diet. The problem of interspecific competition is dealt with in two concrete cases: Lacertidae and Triturus. Great differences in size or corporal shape and behaviour permit coexistence but in the opposite case they separate themselves throughout the area, distributing the biotopes according to their physiological preferences. There are cases (Lacerta schreiberi and Triturus boscai) in which there appears to be a spatial displacement due to a diffuse competition with congenital species. One highlights the importance of the habitat in the food diet of some species, which becomes very clear comparing the tritons with the lizards and amphibians from land habitats. One questions the problem of stability and heterogeneity (climatic and spatial), competition and predation as factors which impel and influence the evolution of communities and species. In relation with studies realized in other areas we see that the herpetological community of Caurel represents the transition from the Mediterranean region to the European shore region, very much in accordance with the climatic and botanical characteristics of the zone, where the seasonality plays an important role just as the glaciarism appears to have determined a Reptile community evolutionally young.