Collaborative Research: Species-level Phylogenetics of Opossums, a Window into South America's "Splendid Isolation"

南美洲是一个岛屿大陆，在过去5000万年的大部分时间里，哺乳动物的历史包括一些祖先物种如何进化成生态复杂的动物群的教科书例子。它还说明了气候变化如何影响生物多样性，以及岛屿动物群如何应对在其他地方进化的入侵物种。不幸的是，大多数关于南美洲哺乳动物进化的知识都来自远离亚马逊和其他高多样性热带地区的化石沉积。然而，由于分子生物学的最新进展，没有化石记录的生物的进化历史现在可以从DNA序列中重建。该项目的主要目标是利用DNA序列和其他类型的数据重建负鼠（南美洲雨林有袋动物）的进化历史。研究结果将用于测试当前关于古代气候变化和生物入侵何时以及如何影响南美洲热带哺乳动物进化的假设。负鼠的分子数据还可以为以前未被怀疑的大规模灭绝或快速物种形成时期提供证据，这些证据可能解释其他生物体的多样性模式。除其他实际应用外，了解现代生物多样性的原因，特别是在目前受到人类活动威胁的热带景观中，对于最大限度地提高及时保护工作的效力至关重要。

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.