Dissertation Research: Evaluating Habitat Change and its Influence on the Decline of Middle Eocene primate Communities in North America

北美始新世灵长类一直是众多关于其适应性多样性和系统发育关系的学术研究的对象。然而，这些灵长类在始新世时期表现出独特的群落演化模式。始新世早期，灵长类物种多样性和物种丰富度迅速增加，到始新世中期，灵长类多样性达到高峰。然而，在始新世中期的后半段，物种数量似乎开始相当迅速地减少。北美灵长类物种多样性的下降归因于气候和栖息地的变化。虽然这些关于气候和栖息地变化的假说已经提出，但它们从未经过严格的检验。本研究旨在探讨始新世中后期灵长类物种多样性下降的原因。具体地说，研究人员将通过对北美西部内陆化石地点的个案研究，评估栖息地变化对始新世后期灵长类物种衰退的影响。研究人员将把栖息地重建的方法与灵长类群落结构变化的评估相结合，以调查当地栖息地如何影响始新世中期西部内陆灵长类群落的衰退。对北美中始新世哺乳动物动物群和现存的新热带哺乳动物动物群的分析将被用来确定：1)利用生态多样性分析确定中始新世西部内陆地区的栖息地特征；2)从食物、体型和运动(或底物偏好)这些功能变量方面确定中始新世以来含有灵长类动物的哺乳动物群落的结构；3)灵长类和共生的树栖哺乳动物群落的生态形态随时间的变化与它们所在的栖息地的关系。

The North American Eocene primates have been the subjects of numerous scholarly studies regarding their adaptive diversity and phylogenetic relationships. However, these primates show a distinctive pattern of community evolution during the Eocene epoch. During the early Eocene intervals, morphological diversity and species richness increased rapidly and by the middle Eocene, primate diversity was at its peak. Yet, during the latter half of the middle Eocene, species numbers began to decrease, it seems, quite rapidly. This decline of primate diversity in North America has been attributed to changes in climate and habitat. While these hypotheses of climate and habitat change have been put forth, they have never been rigorously tested. The purpose of this research is to explore the factors that led to the decline in primate diversity during the later intervals of the middle Eocene. Specifically, the researchers will evaluate the effects of habitat change on the decline of primate species during the latter intervals of the middle Eocene using a case study of North American western interior fossil localities.The researchers will combine methods of habitat reconstruction with the assessment of changing primate community structure in order to investigate how local habitats have influenced the decline of primate communities in the western interior during the middle Eocene. Analyses of North American Middle Eocene mammalian faunas and extant Neotropical mammalian faunas will be used to determine: 1) the habitat characterizations for middle Eocene western interior localities using ecological diversity analysis, 2) the structure of mammalian communities containing primates from the middle Eocene, in terms of these functional variables: diet, body size and locomotion (or substrate preference), and 3) the ecomorphological variation over time in primate and co-occurring arboreal mammal communities in relationship to the habitats in which they are found.