The Role of Phenotypic Plasticity in the Interpretation of Stratophenetic Patterns in the Paleozoic

表型可塑性在解释古生代平流层进化模式中的作用许多进化研究集中在生物群体如何适应和改变面对环境变化。自然选择作用的原材料是生物体的可塑性或可变性？S表现型（生物体基因组成的物理表达，如体型、形状等）。几乎所有的表型都会表现出一定的可塑性，因为所表达的性状是遗传与环境相互作用的结果。然而，表型可塑性与可变环境条件之间的关系仍需要进一步了解。虽然许多生物学研究已经解决了这种与现代生物的关系，甚至延伸到年轻的化石记录，但这一领域的研究一直缺乏更古老的环境。化石记录的力量在于它使我们能够测量一个物种在更长的时间尺度上的变化；但古生物学可以吗？随着时间的推移，对进化生物学的贡献提高了我们对表型和环境之间关系的理解？实现这一目标有两个主要步骤：1。必须准确记录物种内表型变异的地理分布及其与空间环境梯度的对应关系（称为反应规范）。2. 一个物种的反应标准必须经过一段时间的评估。本研究的目的是描述古环境条件与Kope组（奥陶纪，约4.5亿年）岩石中两种三叶虫形状变化之间的关系。在这项研究中，形态学是使用几何形态计量学来测量的，它可以在高分辨率下量化形状变化。古环境变化是通过梯度分析来衡量的，利用化石遗存的分布和丰度来表征环境。初步研究表明，三叶虫Flexicalymene granulosa颅部（头部）形状变化的统计显著部分与该物种保存的环境有关。形状和环境之间的这种关系使我们提出，这种三叶虫物种随时间变化的模式是种群遵循其偏好环境（也称为环境跟踪）的结果。为了验证我们的假设，下一步是系统地追踪这种已建立的关系。为此，我们将把颅形与一般的地质解释（如岩石类型、环境）以及通过Kope组的梯度分析获得的环境量化测量进行比较。在接下来的三年里，密集的野外工作将通过时间和空间提供三叶虫颅形和环境的综合数据集，以此来检验我们的假设。这项研究对理解三叶虫物种内的变异如何促进三叶虫作为一个群体的进化具有直接意义。它使用一种新颖的方法将形态变化与环境变化的高分辨率测量进行比较，这种方法可以用于许多地质环境中的许多生物体。这项研究的一个重要组成部分将是科学研究与科学教育的整合，通过在辛辛那提博物馆中心开发的一个讲习班，旨在为地区科学教师提供地质学和古生物学方面的培训。

The Role of Phenotypic Plasticity in the Interpretation of Stratophenetic Patterns in the PaleozoicBrenda R. Hanke and Andrew J. WebberMany evolutionary studies focus on how populations of organisms adapt and change in the face of environmental changes. The raw material upon which natural selection acts is plasticity, or variability, in an organism?s phenotypes (the physical expression, such as body size, shape, and others, of the genetic make-up of an organism). Nearly all phenotypes will show some plasticity because traits that are expressed result from the interaction of genetics with environment. The relationship between the plasticity of phenotypes and variable environmental conditions, however, still requires further understanding. While numerous biological studies have addressed this relationship with modern organisms, even extending into the young fossil record, this area of research has been lacking in settings that are much older. The power of the fossil record is that it allows us to measure changes within a species over longer time scales; but can paleontology?s contribution to evolutionary biology improve our understanding of the relationship between phenotype and environment over time? There are two primary steps in achieving this goal: 1. the geographic distribution of phenotypic variability within a species and how it corresponds to spatial environmental gradients (known as a reaction norm) must be accurately documented. 2. The reaction norm for a species must then be evaluated over time.The goal of this research is to describe the relationship between paleoenvironmental conditions and variability in the shape of two trilobite species within rocks of the Kope Formation (Ordovician Period, around 450 million years old). In this study, morphology is measured using geometric morphometrics, which quantifies shape change at high resolution. Paleoenvironmental change is measured through gradient analysis, which uses the distribution and abundance of fossil remains to characterize environment. Preliminary research shows a statistically significant portion of shape variability in the cranidium (head) of the trilobite Flexicalymene granulosa is related to the environment in which this species is preserved. This relationship between shape and environment lead us to propose that patterns of change through time in this trilobite species is the result of populations following their preferred environments (also known as environmental tracking). To test our hypothesis, the next step is to systematically track this established relationship through time. To this end, we will compare cranidial shape to general geological interpretations, such as rock type, of environment, and to a quantified measure of environment acquired through gradient analysis in the Kope Formation. Intensive field work conducted over the next three years will provide a comprehensive dataset of trilobite cranidial shape and environment through time and space from which to test our hypothesis.This study has direct implications for understanding how variation within a trilobite species contributes to evolution within trilobites as a group. It compares morphological change to a high-resolution measure of environmental change using a novel approach, which can be used on many organisms in many geological settings. An important component of this study will be the integration of scientific research with science education through a workshop developed at Cincinnati Museum Center designed to provide training for regional science teachers in geology and paleontology.