DISSERTATION RESEARCH: Historical dynamics of American beech at its northern range limit

预计许多树种的分布将因气候变化而向高纬度地区转移。一个物种的迁移能力主要取决于其分布范围的两极边缘种群的个体的扩散和殖民，这些迁移过程的细节很可能决定未来数千年新种群的遗传结构，从而决定它们适应新环境的能力。这项研究试图通过研究冰川退缩后过去向北的迁移和美国东部温带落叶林中一种优势树种目前的遗传种群结构来预测未来，美国山毛榉 通过分析上密歇根州数千年来保存在湖泊沉积物中的花粉和大型化石的遗传数据，该项目将阐明山毛榉模式的重要殖民模式，并展示这些模式如何导致遗传多样性。通过进一步整合这些历史数据与今天山毛榉种群的遗传分析，该项目将有助于了解气候驱动的迁移的长期遗传后果。了解气候变化将如何影响森林和生物多样性对社会很重要，因为我们依赖森林生产许多产品，依赖多样性维持良好运作的环境。 该项目还将有助于森林养护和管理，帮助提出哪些种群在遗传上处于危险之中，需要立即加以养护。此外，该项目将在科学研究过程中培养本科生。

Climate-driven shifts in distribution towards higher latitudes are expected to occur for many tree species. The ability of a species to move will depend mostly upon dispersal and colonization by individuals from populations at the poleward edge of its range, and the details of these migration processes are likely to determine the genetic structure of the new populations for millennia to come, and hence their ability to adapt to their new environment. This research seeks to anticipate this future by examining the past northward migration after glacial retreat and the present genetic population structure of a dominant tree of the temperate deciduous forests of the eastern U.S., American beech. By analyzing genetic data from pollen and macrofossils preserved in lake sediments for thousands of years in Upper Michigan, the project will elucidate the important patterns of colonization by beech patterns and show how these led to patterns of genetic diversity. By further integrating these historical data with genetic analyses of beech populations today, the project will help understand the long-term genetic consequences of climate-driven migration. Understanding how climate change will affect forests and biological diversity is important to society, because we depend upon forests for many products and upon diversity for maintaining a well-functioning environment. The project will also contribute to forest conservation and management by helping suggest which populations are genetically at risk and need immediate conservation attention. Moreover, the project will train undergraduate students in the process of scientific research.