DISSERTATION RESEARCH: Tests of parallel divergence processes in montane plants: links between population differentiation and species diversity patterns

冰川的周期性进退如何影响山区的生物多样性？环境梯度和地理如何影响物种在其分布范围内的多样性结构？研究人员将利用来自北美西部山区六种密切相关的植物物种的数百个DNA序列来解决这些问题。分析建模技术将使他们能够确定物种形成事件是在成对的姐妹物种之间均匀发生，还是在各种不同的情况下发生。随后，研究人员将确定更新世时期（从260万年前到2万年前）剧烈改变山地景观和适宜栖息地的冰川是否影响了物种？随机或可预测的分布。最后，研究人员将调查每个物种内部当前的分子变化是否沿着环境梯度（例如，谷底和山顶之间的温度变化）、地理或冰川期间栖息地的变化分布。从这些分析中获得的知识将帮助研究人员了解生物多样性是如何在山区产生的。它还将有助于阐明气候稳定性与特定环境和地理条件在构建物种内分子多样性分布中的相对重要性。由于气候变化改变了温度和降水制度，生活在山地生态系统中的生物正面临着不确定的未来。随着低海拔地区变得更加温暖和干燥，许多山地生物将被迫向上坡迁移，而已经局限于高海拔地区的生物可能会死亡，因为合适的栖息地将不复存在。了解哪些环境变量会影响植物在整个景观中的分布，将使土地管理者和保护主义者能够抵消物种的减少？人口规模。这项研究将告诉专业人员栖息地适宜性将如何在景观中变化，并帮助他们确定从哪里获得植物材料，以便在重新引入或辅助迁移工作中取得最佳结果。总之，研究结果将通过突出单个物种对不同环境条件的敏感性，为保护山地景观的生物多样性提供相关信息。

How did the cyclical advance and retreat of glaciers affect biodiversity within mountainous regions? How do environmental gradients and geography influence the current structure of diversity within species across their ranges? Researchers will address these questions by utilizing hundreds of DNA sequences from six closely related plant species native to the mountains of western North America. Analytical modeling techniques will allow them to determine if speciation events occurred uniformly among pairs of sister species or if they occurred under a variety of different scenarios. Subsequently, researchers will determine if glaciations that dramatically altered montane landscapes and suitable habitat during the Pleistocene Epoch (from 2,600,000 to 20,000 years ago) impacted species? distributions randomly or predictably. Finally, researchers will investigate if the current molecular variation within each of the species is distributed along environmental gradients (for example, the change in temperature between a valley floor and a mountaintop), by geography, or from the shifting of habitats during glaciations. Knowledge gained from these analyses will help researchers understand how biodiversity was created in the mountains. It will also help elucidate the relative importance of climatic stability versus specific environmental and geographic conditions in structuring the distribution of molecular diversity within species.Organisms living in montane ecosystems are facing an uncertain future as climate change alters temperature and precipitation regimes. Many montane organisms will be forced to move upslope as lower elevations become warmer and drier, and organisms already restricted to the highest elevations may die off because suitable habitat will no longer exist. Knowing what environmental variables influence the distributions of plants across the landscape will allow land managers and conservationists to counteract declines in species? population sizes. This research will inform professionals about how habitat suitability will change across the landscape, and help them to determine from where to source plant material in order to have the best results for reintroduction or assisted migration efforts. In summary, the results will contribute information relevant to preserving biodiversity across montane landscapes by highlighting how individual species are sensitive to different environmental conditions.