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

大多数关于物种分布随气候变化而变化的预测都假定，地理范围在很大程度上是由包括温度和降水在内的非生物胁迫决定的。然而，生态学家通常认为，在这类压力相对较低的地区，物种范围受到捕食或寄生等生物相互作用的强烈影响。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，但对于物种范围内有意义的部分或沿压力梯度的非生物和生物相互作用的相对强度，很少有测试。该项目将使用田间和温室实验来评估授粉对东非干旱梯度上常见的林下植物木槿花性能的影响，为正在进行的对同一系统中的草食植物和植物之间相互作用的研究增添内容。这项工作将通过使用H.meyeri构建不同的预测性分布模型来帮助开发物种分布模型，这些模型结合了多种生物相互作用。这项研究的更广泛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，以及向资源管理者和用户推广。许多传粉者和大型食草动物在非洲和全球都受到威胁，这项工作将有助于展示它们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，并与肯尼亚的国家博物馆和Mpala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.