The history of mammals in South America, an island continent throughout most of the last 50 million years, includes textbook examples of how a few ancestral species can evolve into ecologically complex faunas. It also illustrates how biological diversity is affected by climate change, and how island faunas respond to invading species that evolved elsewhere. Unfortunately, most of what is known about South American mammal evolution comes from fossil deposits that are far from Amazonia and other high-diversity tropical regions. Due to recent advances in molecular biology, however, the evolutionary history of organisms that do not have a fossil record can now be reconstructed from DNA sequences. The main goal of this project is to reconstruct the evolutionary history of opossums, South American rainforest marsupials, using DNA sequences and other kinds of data.
The results will be used test current hypotheses about when and how ancient climate change and biological invasions impacted mammalian evolution in tropical South America. Molecular data from opossums could also provide evidence for previously unsuspected mass extinctions or periods of rapid species formation that might explain present-day patterns of diversity in other organisms. Among other practical applications, understanding the causes of modern biological diversity, especially in tropical landscapes currently threatened by human activity, is important for maximizing the effectiveness of timely conservation efforts.
