Areas of Endemism of the Neotropical Mammals (Mammalia)

The identification of areas of endemism is an essential step in analyses of evolutionary biogeography. Areas of endemism have been defined by the congruency of two or more distributional areas, where there is a general assumption that the endemic taxa have a similar geographic response to historical and environmental factors. Mammals are highly diverse in the Neotropics, and most of them have evolved together with that biogeographical region. However, there are few hypotheses of areas of endemism that may be related with the evolution of the mammals in the Neotropics. We analyzed a matrix of 2052 taxa (families, genera and species) to identify the areas of endemism of the Neotropical mammals. The search of areas of endemism was performed using the Analysis of Endemicity method in a grid of 2 degrees latitude - longitude. The analysis resulted in 101 areas and 498 endemic taxa, the areas partially matched with 65 biogeographical patterns previously identified by other authors. The Neotropical region is composed of nine areas of endemism and showed multiples boundaries, these characteristics suggest a dynamic pattern. Two complex areas of biotic interchange corresponded with the Mexican and Southamerican transitional zones. On one side, the congruence of areas of endemism of mammals with other biogeographical patterns suggests that historical and ecological factors have shaped the structure of those areas. On the other side, the incongruence of some areas of endemism supports a biogeographical system without hierarchy.