DISSERTATION RESEARCH:Ecological interactions mediate the effects of climatic stress on populations: dissecting the direct and indirect effects of climate on plants

大多数物种分布随气候变化变化的预估都假定地理范围在很大程度上取决于包括温度和降水在内的非生物胁迫。然而，生态学家普遍认为，这些压力相对较低的地区的物种范围受到生物相互作用（如捕食或寄生）的强烈影响。尽管这一长期存在的假设与大多数未来物种分布预测背后的假设相矛盾，但在物种范围的有意义的部分或沿着应力梯度，对非生物和生物相互作用的相对强度的测试很少。该项目将利用田间和温室试验来评估授粉对东非干旱梯度下常见的林下植物木芙蓉生长性能的影响，这是对同一系统中植物之间的草食和相互作用正在进行的研究的补充。这项工作将有助于发展物种分布模型，通过使用H. meyeri来构建预测分布模型，这些模型在多种生物相互作用的结合中有所不同。研究结果将有助于表明，为了理解物种如何受到温度和降水变化的影响，什么时候必须包括生物相互作用。这项研究的更广泛的影响包括为保护生物多样性提供科学信息，为学生提供国家和国际培训，并与资源管理者和用户接触。在非洲和全球范围内，许多传粉媒介和大型食草动物受到威胁，这项工作将有助于揭示它们的灭绝对生态系统功能的潜在影响。该项目将培训美国和肯尼亚的本科生和一名美国博士生，并与肯尼亚国家博物馆和姆帕拉研究中心合作。

Most projections of shifts in species distributions with climate change assume that geographic ranges are strongly determined by abiotic stresses including temperature and precipitation. However, ecologists have generally thought that species ranges in areas where such stresses are relatively low are strongly influenced by biotic interactions such as predation or parasitism. Though this long-standing hypothesis contradicts the assumptions behind most projections of future species distributions, there are few tests of the relative strength of abiotic and biotic interactions across meaningful portions of species ranges or along stress gradients. This project will use field and greenhouse experiments to assess the effect of pollination on performance of the common, understory plant Hibiscus meyeri along an aridity gradient in East Africa, adding to on-going studies of herbivory and interactions between plants in the same system. The work will help develop species distribution modeling by using H. meyeri to construct predictive distribution models that vary in their incorporation of multiple biotic interactions. Results will help to show when biotic interactions must be included to understand how species will be influenced by changes in temperature and precipitation.The broader impacts of this research include provision of scientific information for the conservation of biodiversity and national and international training for students and outreach to resource managers and users. Many pollinators and large herbivores are threatened in Africa and around the globe, and this work will help show the potential effects of their extirpation on the functioning of ecological systems. The project will train U.S. and Kenyan undergraduate students and a U.S. Ph.D. student, and collaborate with the National Museums and the Mpala Research Centre in Kenya.