Variação morfológica inter populacional de cascavel, Crotalus durissus, Linnaeus 1758 (Serpentes, Viperidae) no Nordeste Brasileiro

Abstract

The rattlesnake Crotalus durissus is the only species of the genus present in Brazil, being characteristic of open arid regions and, possibly, found in forest areas. Currently 10 subspecies are recognized, evidencing the taxonomic problem in which the species is involved. Studies aimed at describing the morphology of the animals have been the basis for the description of new species and have also helped in the identification of variations associated with food adaptations and the use of space. This study sought to verify the existence of meristic and morphometric differences in different populations of C. durissus in Northeast Brazil. Thirty-five copies were analyzed, from 18 municipalities and 5 regions. The Principal Components Analysis and Cluster Analysis were used to verify morphological differences between the individuals considering the populations and the Moran I correlogram was used to verify the presence of spatial structure. Specimens of C. durissus showed morphological similarities among all populations. The PCA of the meristic and morphometric variables did not clearly separate the populations, indicating the sharing of morphological characteristics. Nevertheless, there was a morphometric distinction among the populations of the metropolitan region and the center-south sharing the some space in the same morphometric space while the population of Feira de Santana and São Francisco staying together in the same gathere in another morphometric. There was a spatial structure, evidencing that geographically close populations also have greater morphometric similarity. However, nearby populations also exhibited morphometric variation. The Cluster showed that the most similar populations were those of the metropolitana region and the centro-sul and most dissimilar population was that of Maranhão. The morphological similarity found in the populations of C. durissus reinforces the common origin of the species, giving subsidies for the definition of absence of distinct species within C. durissus. Thus, the variations found here are possibly of ontogenetic origin.