Species Level Processes and the Evolutionary Dynamics of Agnostid Trilobites

9804955SmithI建议对中寒武世Ptychagnostidae(三叶目，Agnostida)进行物种水平的分析，以检验该支系内物种的微观进化属性与宏观进化模式之间的关系。具体地说，我的目标是测量表型变异性，并根据文献、博物馆和野外收藏记录所有Ptychagagnostidae物种的地理和地层范围。这些属性在确定物种后代数量方面的作用将在使用Westrop等人的分支图构建的系统发育图的背景下进行评估。(1996)和分类群的地层产状。目前正在建立一个以文献为基础的数据库，但对表型变异性的可靠衡量需要博物馆藏品中提供的大量标本样本，并辅之以更多的实地收藏。拟议的项目将建立在对中寒武世Ptychagnostidae的广泛先前研究的基础上，并将具体解决以下假设：1)一个物种的表型变异性水平以及地理和地层范围与一个物种产生的后代数量相关，以及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，同时最小化进化分化。对这些假说的评价，对于理解Ptychagnostidae的进化动力学，以及海洋无脊椎动物寒武纪辐射期间和地球历史其他时期的进化速度和方式都具有重要意义。

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.