Origin and evolution of the avifauna at the highland forests in Northeastern Brazil: understanding the past connections between Amazon and Atlantic Forest

Abstract

There are very few studies in northeastern Brazil, a region that is home to a variety of environments used to propose hypotheses and models of diversification, but have not had an empirical contribution to advance on these discussions, particularly with the contribution of molecular biology. In northeastern Brazil, forest refuges are result from processes of expansion and shrinkage of forests during climate fluctuations and were cited as the hypotheses to explain the occurrence of disjunct rainforest of the Amazon, in the coastal region, as well as forest enclaves of mountains located in the area of Caatinga, a semi-arid region. These enclaves, known as "Brejos de Altitude" occur between c. 500 and 1,100 meters above sea level, where orographic rains ensure higher levels of rainfall to 1200mm / year. Some authors suggest that the "Brejos de Altitude" were part of one of the corridors connecting the Atlantic Forest and Amazon during the warmer periods of the Plio-Pleistocene. However, phylogenetic and phylogeographic studies suggest that the connections between the Atlantic Forest and Amazon occurred in different geological periods from the Miocene, c. 26 Ma, which raises questions that support the "Brejos de Altitude" as a unique biogeographical entity. The difficulty to test this hypothesis is associated with the limited availability of material covering the entire distrution of the "Brejos de Altitude" and other related areas for use in molecular analyzes. Moreover, these environments are considered the most endangered in the Atlantic Forest and factors that generate these threats are still occuring today. Which may compromise the future existence of the organisms that can be used as evidence for the above studies.In recent years several studies have shown the importance of integrating phylogenetic information on conservation programs. For example, the combination of dated phylogenies with models of distribution of the organisms allow us to understand the effects of climate change in the past, and use them for planing the conservation in the face of current and future climate change. Studies of molecular phylogeny and distribution modeling have shown that different bird species respond differently against climate change. The information of how species have responded in the past against the intense climate change can be used to study the degree of susceptibility and response of biota to current and future climate change. This knowledge have a fundamental importance in the context of global warming already observed and expected for several regions of the planet. Therefore, is essential to the development of public policies to mitigate the effects of these changes on biodiversity. This proposal aims to make a comprehensive analysis studying the historical relationship between the areas of "Brejos de Altitude", the Amazon and the Atlantic Forest, and relate it to geological events and / or changes in the landscape that may have been responsible for the exchange biodiversity observed between these areas. The aim of this study is to investigate different groups of birds to understand the current disjunct distribution (ie. the Atlantic Forest, the Amazon and the "Brejos de Altitude") is the result of a single large event of fragmentation / connection of tropical forests during the Pleistocene; different events of fragmentation in different periods of global cooling; or long-distance dispersal events. We will reconstruct the phylogenetic relationships of different genera, species and populations of birds that occur in the "Brejos de Altitude" in the Amazon and Atlantic Forest to infer historical and ecological processes determined their diversification. So we will improve our understanding of the historical relationship between these areas. (AU)