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

南美洲是一个岛国大陆，在过去5000万年的大部分时间里，哺乳动物的历史包括一些教科书上的例子，说明几个祖先物种如何进化成生态复杂的动物群。它还说明了生物多样性如何受到气候变化的影响，以及岛屿动物如何应对在其他地方进化的入侵物种。不幸的是，人们对南美哺乳动物进化的了解大多来自远离亚马逊和其他高多样性热带地区的化石沉积物。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史现在可以从DNA序列中重建出来。该项目的主要目标是利用DNA序列和其他类型的数据重建南美热带雨林有袋类负鼠的进化史。这些结果将被用来检验目前关于古代气候变化和生物入侵何时以及如何影响热带南美洲哺乳动物进化的假设。来自负鼠的分子数据也可以为以前未被怀疑的大规模灭绝或物种快速形成时期提供证据，这可能解释其他生物今天的多样性模式。在其他实际应用中，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有效性非常重要。

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.