Species Level Processes and the Evolutionary Dynamics of Agnostid Trilobites

不可知三叶虫的物种水平过程和进化动力学

• 批准号: 9804955
• 负责人: Loren Smith
• 金额: $ 5.93万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-15 至 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9804955&HistoricalAwards=false
• 关键词: Species; Level; Processes; Evolutionary; Dynamics

9804955SmithI propose a species-level analysis of Middle Cambrian Ptychagnostidae (Trilobita, Agnostida) in order to test hypotheses relating microevolutionary attributes of species to macroevolutionary pattern within this clade. Specifically, I aim to measure phenotypic variability and document the geographic and stratigraphic ranges of all species of Ptychagnostidae based on literature, museum, and field collections. The role of these attributes in determining the number of descendants of a species will be assessed in the context of a phylogeny constructed using the cladogram of Westrop et al. (1996) and the stratigraphic occurrence of taxa. A literature-based database is currently being constructed, yet robust measures of phenotypic variability require large samples of specimens available in museum collections and supplemented by additional field collections. The proposed project will build upon extensive prior research on Middle Cambrian Ptychagnostidae and will specifically address the hypotheses that: 1) levels of phenotypic variability and the geographic and stratigraphic range of a species are correlated with the number of descendants produced by a species, and 2) the distribution of species of Ptychagnostidae within a morphospace should be constant in order to avoid competition while minimizing evolutionary differentiation. The evaluation of these hypotheses has great significance for understanding both the evolutionary dynamics of the Ptychagnostidae and the tempo and mode of evolution during the Cambrian radiation of marine invertebrates and during other intervals of Earth history.

9804955SmithI提出了一个中寒武世Ptychagnostidae（三叶虫属，Agnostida）的种水平分析，以检验将物种的微观进化属性与该分支内的宏观进化模式相关联的假设。 具体来说，我的目标是测量表型变异和文件的地理和地层范围的所有物种的Ptychagnostidae的文献，博物馆和现场收藏的基础上。 这些属性在确定一个物种后代数量方面的作用将在使用Westrop等人（1996）的分支图和分类群的地层出现构建的系统发育背景下进行评估。 目前正在建立一个基于文献的数据库，但强大的表型变异性的措施需要大量的标本在博物馆收藏，并辅以额外的实地收集。 拟议的项目将建立在对中寒武世Ptychagnostidae的广泛研究的基础上，并将具体解决以下假设：1）一个物种的表型变异水平以及地理和地层范围与该物种产生的后代数量相关，和2）Ptychagnostidae的物种在形态空间内的分布应该是恒定的，以避免竞争，同时最大限度地减少进化分化 这些假说的评价具有重要意义的理解Ptychagnostidae的进化动力学和海洋无脊椎动物在寒武纪辐射和地球历史的其他间隔期间的演化克里思和模式。