Padrões de distribuição e riqueza de espécies troglóbias no Brasil

Abstract

Caves have environmental conditions different from the surface, subjecting the subterranean fauna to different selective pressures. Species highly adapted to the subterranean environment are called troglobias, and share an evolutionary history of adaptation in aphotic environments with few nutrients. One of the explanations for the emergence of these species is provided by the hypothesis of Climate Change, in which cave populations maintained a gene flow with the surface, but glacial events and ecological factors ended up isolating them geographically and genetically. An alternative explation is provided by the Adaptive Deviation hypothesis, in which the populations that invaded the caves in search of resources suffered new selective pressures, and when the colonization was successful the population expanded in the underground habitat, reducing the gene flow with the epigeal populations. The goal of this study is to analyze which process determines the distribution and richness patterns of troglobic species in Brazil, to identify the influence of paleoclimatic events in the region and to analyze whether the distance between caves affects the structuring of the community. In addition to estimates of tetrapod richness we also used paleoclimatic data from the last five million years, including temperature, precipitation and primary productivity. The results showed that the regions with the greatest wealth are highly correlated with the greatest variation in temperature, and the least variation in precipitation. Data on primary productivity and tetrapod richness did not show significant correlation.