Ecological and Historical Correlates of Iberian Herpetofaunal Diversity: An Analysis at Regional and Local Levels

Abstract

Correlation of herpetofaunal diversity with ecological and historical factors is considered at regional and local levels in the Iberian peninsula. A brief paleogeography of Iberia is presented and used to explain herpetofaunal diversity patterns at the regional level. These patterns of diversity are discussed in terms of several causal hypotheses of species diversity. Species richness and species abundances at the local level (Catdiz Province, Spain) are analysed for correla- tions with variables of climate, vegetation, soil and area. Gradients in species diversity are not observed at the regional level. No consistent correlations between environmental factors and species diversity are demonstrated at the local level. Most of the species are abundant in agricultural areas as well as undis- turbed habitats. The exponent (z) obtained for herpetofaunal species-area relationships within Iberia falls within the range observed in insular (ecologically unsaturated) situations. We advance the hypothesis that profound historical per- turbations can preclude latitudinal diversity gradients by creating an environment conducive to ecologically broad-niched species. We interpret the absence of diversity gradients within Iberia as an epiphenomenon arising from the eco- logically generalized habits of Iberian amphibians and reptiles; data from those species which we observed at the local level of our analysis serve as examples.