Relationship Between Variation and Evolution in Fossil Stickleback Fish

9870337贝尔人们早就知道，在相关种群或物种内部和之间的表型变异模式是相似的。 这一观察结果有时被解释为意味着进化变化偏向于最大变异的方向。 另一种解释是，有利于向某个方向进化的因素也塑造了种群内的变异模式。 Gmax（种群内最大加性遗传方差的多元方向）和Z（种群间多元进化的方向）是如何朝着同一个方向发展的，这个问题一直没有一个令人满意的答案，这个问题一直困扰着从数量遗传学到古生物学等领域的工作者。 这项拟议中的研究将利用化石记录中的时间因素来帮助解决这个棘手的问题。 这项研究的基础是一个非凡的存款化石threespine棘鱼，Gasterosteus doryssus，从晚中新世，中部成员的特拉基组是中西部内华达州。 丰富的，保存完好的标本展示了惊人的模式，地层变化的大小，装甲，并在采石场，已被用于在以前的几项研究的主要研究员鳍射线数。 存款本身具有特殊的属性，提供了理想的条件，使大型刺鱼样本在定期的时间间隔超过数千年。 这些特性中最重要的是不间断的年度层压（纹）的存在。 此外，古生态学证据和与现存三棘鱼的类比表明，化石序列中的样本代表了具有祖先-后代关系的种群（即，血统）。 这正是研究种群内变异与进化方向之间联系所需要的，从这一化石谱系获得的形态测量数据将用于研究化石样本内最大表型变异的多变量方向P与连续样本之间的多变量进化方向Z之间的关系。 P和Z的方向将使用11至24个大样本的形态测量数据，以1000年的间隔进行估计。 将比较P和Z之间的Angeles，以查看样本内的P是否倾向于偏移它与下一个样本之间的演化方向（Z），或者P是否倾向于摆动以匹配它与前一个样本之间的Z方向。 这两种效应都可能发生，使用化石谱系将允许对经常观察到的种群内和种群间变异方向相似性的原因进行批判性分析。 这项研究将是第一次利用化石记录提供的关键时间元素进行此类分析。 这项研究不仅将是第一次这样的分析，而且还将有助于形态测量学的方法发展和越来越多的关于棘鱼进化的文献。

9870337BellIt has long been known that patterns of phenotypic variation within and among related populations or species are similar. This observation has sometimes been interpreted to mean that evolutionary change is biased toward the direction of greatest variation. An alternative explanation is that the same factors that favor evolution in a certain direction also shape patterns of variation within populations. There has never been a satisfactory answer to the question of how Gmax, the multivariate direction of greatest additive genetic variance within populations, and Z, the direction of multivariate evolution between them, become oriented in the same direction.This problem has puzzled workers in fields ranging from quantitative genetics to paleontology since. The proposed research will exploit the element of time in the fossil record to help resolve this stubborn problem. The basis for this study is an extraordinary deposit of fossil threespine stickleback fish, Gasterosteus doryssus, from the late middle Miocene, middle member of the Truckee Formation is west-central Nevada. Abundant, beautifully-preserved specimens exhibit striking patterns of stratigraphic variation for size, armor, and fin ray number in a quarry that has been used in several previous studies by the Principal Investigator. The deposit itself has special properties that offer ideal conditions to make large stickleback samples at regular time intervals over thousands of years. Not the least important of these properties is the presence of uninterrupted annual laminations (varves). Furthermore, paleoecological evidence and analogy with extant threespine stickleback show that samples from the fossil sequence represent populations with ancestor-descendant relationships (i.e., a lineage). This is exactly what is needed to examine the link between variation within populations and the direction of evolution.Morphometric data obtained from this fossil lineage will be used to examine the relationship between the multivariate direction of greatest phenotypic variance within fossil samples, P, and the direction of multivariate evolution, Z, between successive samples. The directions of P and Z will be estimated using the morphometric data from 11 to 24 large samples spaced at 1000-year intervals. Angeles between P and Z will be compared to see if P within a sample tends to bias the direction of evolution (Z) between it and the next sample, or whether P tends to swing around to match the direction of Z between it and the previous sample. Both effects may occur.Use of a fossil lineage will allow a critical analysis of the cause for the often-observed similarity between the direction of variation within and among populations. The proposed research will be the first such analysis that utilizes the crucial element of time provided by the fossil record. Not only will the proposed research be the first such analysis, but it will also contribute to methodological developments in morphometrics and the growing literature on stickleback evolution.