Distribution patterns of Kielmeyera (Calophyllaceae): the Rio Doce basin emerges as a confluent area between the northern and southern Atlantic Forest

Abstract

The Atlantic Forest is one of the most diverse and threatened tropical forests in the world, and the Rio Doce valley seems to represent a limit between biotas from its southern and northern portions. In the present study, we investigated the distribution of Kielmeyera (Calophyllaceae), a woody, typically wind-dispersed genus, with a high endemism rate in the Atlantic Forest. The 351 specimens analysed, representing 21 of 22 species of Kielmeyera from the Atlantic Forest, pointed to a complete dissimilarity between species composition in the southern (Rio de Janeiro state) and northern (Bahia state) portions of the forest. However, the Rio Doce valley in Espírito Santo state, rather than being a limit between these two portions, appear to represent a confluent area. The northern boundary of species from the southern portion is the São Mateus basin, whereas the southern boundary of species from the northern portion is at the Litorânea do Espírito Santo basin. Most specimens of Kielmeyera were collected in areas that currently are not remnants of original vegetation and that are not within any conservation unit, suggesting that an imminent loss of biodiversity is taking place. Studies comprising a broad range of functionally and phylogenetically distinct taxa make individual patterns of distribution obscure and overlook the conservation needs for specific groups. Therefore, our study on the distribution of Kielmeyera in the Atlantic forest highlights the importance of biogeographic analyses of less inclusive taxa of a flora.

Keywords

• biogeography
• conservation
• endemism
• geographic barrier