North american biodiversity: testing the effects of phylogeny and biogeography in late cretaceous and cenozoic mammals

了解哪些因素影响不同环境中的物种多样性，对于我们预测气候变化的后果至关重要。通过回顾过去的一段时间，我们可以开始了解变化的长期后果，否则我们只能在很短的时间范围内观察到这些变化。 许多因素会影响物种多样性，包括不同群体从祖先那里继承的特征。为了了解祖先的特征，我们需要一棵解析良好的家谱。我对孕育了鲸鱼的陆地哺乳动物群体的辐射很感兴趣。新的数据显示，鲸鱼是偶蹄目动物(牛、猪、骆驼和河马)的后代，但我们并不完全了解鲸鱼与其灭绝的祖先之间的关系的细节。这项研究将澄清这些关系，并允许研究这一群体5400万年历史上的多样性模式。 其他外部因素，如物种如何在各大洲分布，以及它们如何随时间变化，也可以告诉我们许多关于这些物种可能如何应对重大变化的信息。这项提案将阐述从7000万年前的恐龙时代开始，到6500万年前小行星撞击后的主要气候变化，5600万年前全球迅速变暖，以及大约3400万年前开始缓慢降温之后，整个北美的哺乳动物物种多样性和分布是如何变化的。在这段时间里，有一些证据表明，在加拿大西部发现的一些化石是地方性的，在更南边的地方是未知的，这项提议将测试这些差异是否得到了很好的支持，以及我们是否应该认为加拿大西部属于一个单独的生物区，该生物区对变化的反应不同。

Understanding which factors affect species diversity in different environments is critical to our ability to predict the consequences of climatic changes. By looking at past periods of time we can begin to understand the long-term consequences of changes that we can otherwise only observe over very brief time scales. A number of factors can affect species diversity, including features that different groups inherit from their ancestors. In order to understand ancestral features, we need a well-resolved family tree. I am interested in the radiation of the group of terrestrial mammals that gave rise to whales. New data show that whales are descended from one group of ungulates, the artiodactyls (cows, pigs, camels and hippos), but we don't fully understand the details of the relationships of whales to their extinct ancestors. This research will clarify these relationships and allow study of diversity patterns over the 54 million year history of this group. Other external factors, such as how species are distributed across continents, and how they change over time, can also tell us a great deal about how those species may respond to major changes. This proposal will address how mammalian species diversity and distribution across North America changed over the time period from the age of dinosaurs, 70 million years ago, through the major climatic changes following the asteroid impact 65 million years ago, rapid global warming 56 million years ago, and slower cooling beginning about 34 million years ago. There is some evidence over this time period that some fossils found in western Canada are endemic and are not known from further south, and this proposal will test whether these differences are well supported and whether we should consider western Canada to belong to a separate bioregion that responded differently to change.