The limits and drivers of phenotypic variation and their effects on Cenozoic mammalian herbivore diversity and disparity

表型变异的限制和驱动因素及其对新生代哺乳动物草食动物多样性和差异的影响

• 批准号: RGPIN-2017-03827
• 负责人: Theodor, Jessica
• 金额: $ 1.75万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709745
• 关键词: limits; drivers; phenotypic; variation; their

Loss of biodiversity has cascading effects on ecosystems, especially loss of large herbivorous mammals. The only data on long-term response to rapid changes in climate comes from the fossil record, a laboratory of replicate climate experiments without human influence. The long-term goal for my research program is to understand how properties of species, such as rates of extinction and species splitting and the origin of new morphologies, interact with environmental factors to regulate diversity and morphological variation of herbivores. One hypothesis is that slower-splitting lineages accumulate more morphological differences than rapid ones. The fossil record of ungulates can be used to test this hypothesis. Testing this hypothesis requires a fully resolved evolutionary tree, but the relationships of the lineages of living artiodactyls to the earliest fossils are problematic, because these specimens are beyond the age range for successful ancient DNA sampling, and the morphological characteristics used are strongly convergent. Using CT scans, we will characterize the morphology of the base of the skull of early artiodactyls, which is informative because this region develops very early and seems less prone to convergence. With this information, we will test several hypotheses about the early radiation of artiodactyls: whether the earliest artiodactyl lineages represent a series of stem groups or represent a single radiation; and whether the camels are part of a wider radiation that is more closely related to ruminants (traditional morphological interpretation), or a basal lineage not closely related to them (but showing strong morphological convergence) as molecular data suggest. We will identify major developmental shifts in tooth regions and document the pattern and timing of shifts in the evolution of herbivory to see whether these changes in the regions in the toothrow correlate with major changes in dental function. Mammalian teeth have different shapes in regions. This likely evolved by shifting the boundaries of gene expression within the jaw. Identifying these shifts in ungulates with “molarized” anterior teeth, will allow testing whether shifts are tied to changes in the network of regulatory genes, and whether these change dental function and diet. These changes will be used to tie to other work on the genetic regulation of the tooth regions in mammals to provide an integrated understanding of the limits on morphological disparity. We will test the effects of external factors, such as latitude, climatic and vegetation changes, on herbivore size distributions, and continue to collect high latitude data from Saskatchewan to allow testing of biogeographic hypotheses testing the effects of environmental factors through studies of size evolution in herbivore lineages and communities, and explore the role of the evolution of smaller herbivores on larger ones.

生物多样性的丧失对生态系统产生了级联效应，特别是大型食草哺乳动物的丧失。关于气候快速变化的长期反应的唯一数据来自化石记录，这是一个在没有人类影响的情况下重复气候实验的实验室。