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

[902984]异质性，即发育速度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。记录异时性完全需要了解生长率、系统发育关系以及假定祖先和后代的个体发育大小和形状变化。本研究的目的是了解异时性在鳍足动物起源和进化中的作用，鳍足动物是一种鲜为人知的小型底栖、胶结、泛热带、隐栖无脊椎动物，具有很长的化石记录（三叠纪-近代）和新颖的形态。我们将使用简约理论为基础的形态学系统发育方法，来建立关于酸腹鱼物种和属之间的关系，以及酸腹鱼与其他关节腕足动物之间关系的有力假设。我们将通过分析连续壳生长层的微样品的氧同位素组成来记录ides生长速率，以量化整个个体发育过程中的尺寸-年龄-生长关系。最后，我们将利用多元形态计量学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范围。系统发育、地球化学和形态计量学的结果将结合起来，以测试是否，以及以何种方式，异时性对黑尾石的起源和进化负责。这项研究的结果将通过计算所有三个主要组成部分：系统发育关系、生长速度、形状和大小变化，为化石记录中的异时性提供罕见的、严格的测试。

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.