USING BIOTIC HISTORY TO INFER ENVIRONMENTAL HISTORY IN AMAZONIA

Earth history —especially through tectonics, landscape change, and climate change— influences the spatial distribution of populations of organisms and consequently leads to isolation, differentiation, and the formation of new species and lineages over time. Because of that close linkage between Earth history and biotic diversification, we can also use information about the latter to make inferences and predictions about Earth history and even "test" alternative geological hypotheses.

In recent decades our ability to gather genomic data on large numbers of organisms has significantly increased our understanding of their phylogenetic and biogeographic history. Also, refined methods of dating these phylogenies means that more precise linkages between Earth history and biotic diversification are becoming more feasible.

Here, we use the phylogenetic, biogeographic, and temporal history of Amazonian birds to test distinct geological hypotheses about the origin of the Amazonian drainage pattern. These results strongly support a Plio-Pleistocene origin of the major drainage system. At the same time, emerging data on the genetic structure of populations imply that the influence of hydrological change on the biota has taken place at different spatial and temporal scales. These data indicate that although many groups have had a history in Amazonia extending back as far as the end-Paleogene, most of the diversity we see today reflects a Plio-Pleistocene evolutionary history. Yet, there are still many questions about the environmental drivers responsible for this diversity, but only an integrated view of Earth and biotic history is likely to provide robust answers.