Importância de fatores ecológicos, filogenéticos e alométricos na variação da forma do crânio roedores

Abstract

Rodentia is the most specious order in the world, a pattern mainly observed in the Neotropics, including Brazil as well, according to regional and national species lists. It has cosmopolitan distribution with a great diversity of diets and locomotive habits. Its key synapomorphies are cranial and dental characteristics. Accordingly, I used the skull as the object in this study, analyzing its interaction with allometric factors, diet and phylogeny. The 32 species utilized in this study occur in Espírito Santo state, Brazil, and belong to 7 families of the Order. The tool used in this investigation was the geometric morphometry, using in the data analyses multivariate statistical tests, discriminant analyses, regressions and analysis of canonical variables. No sexual dimorphism was observed when all species were analysed, but there was differentiation in the shape and size of the skull. Comparisons between herbivores and insectivores showed that there are morphological differences between species with different diets, even when they have a close phylogenetic relationship. Still, the trees recovered, based on cranial characters, had the same result in all views, managing to maintain virtually all kinship relationships between families correctly (only replacing Sciuridae and Dasyproctidae). Allometry, however, is not a variation factor in the skull of rodents, reaching negligible regression values. It was then shown that it is possible to differentiate different types of diet and kinship relations by the geometric morphometry of the rodent skull.