Investigating Heterochrony in the Fossil Record: A Geochemical, Morphometric, and Phylogenetic Study of Thecideidina (Brachiopoda), Triassic-Recent.

9902984 CarlsonHeterochrony，发育速率和时间变化的进化结果，被认为是进化发生的最重要手段之一。 记录heterochrony完全需要的增长率，系统发育关系，和个体发育的大小和形状的变化，为假定的祖先和后代的知识。 本研究的目的是了解heterochrony在thecideidine腕足动物的起源和演化的作用，一个鲜为人知的小，底栖，胶结，泛热带，神秘的无脊椎动物与长期的化石记录（三叠纪-最近）和新的形态。 我们将使用简约为基础的，形态系统发育的方法来发展thecideidine物种和属之间的关系，和thecideidines其他关节腕足动物的强大的假设。 我们将记录thecideidine增长率通过分析连续壳生长层的微量样品的氧同位素组成，以量化整个个体发育的大小-年龄-生长关系。 最后，我们将利用多变量形态测量方法来记录伴随个体发育大小增加的形状变化，并描述观察到的成年形态的范围。 系统发育，地球化学和形态测量的结果将结合起来，以测试是否，以及以何种方式，异时性是负责的起源和演化thecideidines。这项研究的结果将提供一个罕见的，严格的测试在化石记录的异时性占所有三个主要组成部分：系统发育关系，生长速度，形状和大小的变化。

9902984CarlsonHeterochrony, the evolutionary consequences of changes in the rate and timing of development, is considered to be one of the most important means by which evolution occurs. Documenting heterochrony fully requires knowledge of growth rates, phylogenetic relationships, and ontogenetic size and shape change for putative ancestors and descendants. The goal of this study is to understand the role of heterochrony in the origin and evolution of thecideidine brachiopods, a poorly understood group of small, benthic, cemented, pan-tropical, cryptic invertebrates with a long fossil record (Triassic - Recent) and novel morphologies. We will use parsimony-based, morphologic phylogenetic methods to develop robust hypotheses of relationship among thecideidine species and genera, and of thecideidines to other articulated brachiopods. We will document thecideidine growth rates by analyzing the oxygen isotopic composition of microsamples of successive shell growth layers, to quantify size-age-growth relationships throughout ontogeny. Finally, we will utilize multivariate morphometric methods to chronicle shape change that accompanies ontogenetic size increase and characterizes the range of observed adult morphologies. Phylogenetic, geochemical, and morphometric results will be combined to test whether, and in what ways, heterochrony is responsible for the origin and evolution of thecideidines. The results of this study will provide a rare, rigorous test of heterochrony in the fossil record by accounting for all three primary components: phylogenetic relationship, growth rate, and shape and size change.