Analysis of the spatial and temporal dynamics of marine bivalve evolution: Combining molecular and densely-sampled fossil data

蛤蜊在现代和古代的淡水和海洋环境中种类繁多，今天有9,000多个物种。现代海洋蛤在经济上非常重要，不仅是人类的食物，还因为它们是人类赖以生存的其他动物的食物，如鱼类。尽管有这种多样性和重要性，但该群体的进化历史还没有得到很好的理解，该项目将对蛤的5亿年进化历史进行更详细的了解。该项目将利用DNA序列以及现代和化石物种的解剖信息来重建进化模式。此外，这些信息将被用来考虑各种关键问题，如群体的进化速度如何随时间而变化，以及从DNA序列研究中获得的进化速度信息与从化石研究中收集的信息的差异程度。该项目还将考虑为什么热带地区的蛤物种比极地地区的蛤物种更多样化，以及生态差异如何影响进化速度。这项研究将为本科生，研究生和博士后学者提供培训，其结果将用于制定高中课程计划，重点是灭绝的原因和后果。该项目旨在利用丰富的海洋双壳类化石记录中的信息，沿着现有物种的遗传信息，重建高度多样化的双壳类分支的进化模式。这组，因为它在寒武纪时期演变，在物种多样性波动显着，并提供了一个特殊的机会，考虑如何从化石和现存类群的信息可以纳入系统发育研究。该项目还将重点关注各种生态特征，包括幼虫类型，如何影响种群的物种形成和灭绝速度。该项目将首先涉及利用基因库中的DNA序列信息沿着形态学信息，为所有现存的双壳类家庭建立一个关系假设。然后，建立在家庭水平的系统发育，一个物种水平的系统发育跨越所有的双壳类将开发与海洋和化石类群的特别关注。将进行测试，以确定在适用于基因和化石为基础的生物遗传学的替代进化模型下多样化率的差异。另一个要素是使用这些生物学原理来检验为什么双壳类和大多数其他类群一样，表现出纬度多样性梯度的假设。以前的研究，这些多样性梯度主要集中在现存的陆生类群。这项研究将提供一个机会，在海洋生物中更详细地考虑这个问题。此外，这项研究，通过纳入化石类群，将考虑纬度多样性梯度如何随着时间的推移而变化，增加了一个重要的时间组成部分不经常considered.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Clams are diverse and abundant in both modern and ancient freshwater and marine environments, and today more than 9,000 species exist. Modern marine clams are economically very important not only as food for humans but also because they serve as food for other animals that humans depend on, like fish. In spite of this diversity and importance, the evolutionary history of the group is not well understood, and this project will develop a more detailed understanding of the 500-million-year evolutionary history of clams. This project will use information from DNA sequences as well as from the anatomy of modern and fossil species to reconstruct evolutionary patterns. Moreover, this information will be employed to consider various key questions such as how the pace of evolution in the group has varied through time, and further the extent to which information on rates of evolution derived from the study of DNA sequences differs from that information gathered from the study of fossils. The project will also consider why clam species in the tropics are more diverse than those found in polar regions, and how differences in ecology influence rates of evolution. This research will provide training for undergraduates, graduate students, and a postdoctoral scholar, and the results will be used to develop high school lesson plans that focus on the causes and consequences of extinction. This project aims to reconstruct evolutionary patterns in the highly diverse bivalve clade using information from the rich marine bivalve fossil record, along with genetic information from extant species. This group, since it evolved in the Cambrian period, has fluctuated significantly in species diversity and provides an exceptional opportunity to consider how information from fossil and extant taxa can be incorporated into phylogenetic studies. The project will also focus on how various ecological traits, including larval type, have influenced rates of speciation and extinction in the group through time. The project will first involve developing a hypothesis of relationship for all extant bivalve families using information on DNA sequences housed in GenBank, along with information from morphology. Then, building on the family-level phylogeny, a species-level phylogeny spanning all of Bivalvia will be developed with an especial focus on marine and fossil taxa. Tests will be conducted to ascertain differences in diversification rates under alternative evolutionary models applied to genetic and fossil-based phylogenies. An additional element will be to use these phylogenies to test hypotheses on why bivalves, like most other groups, show latitudinal diversity gradients. Previous studies of these diversity gradients have primarily focused on extant terrestrial taxa. This study will provide an opportunity to consider this issue in greater detail in marine organisms. Further, the study, through incorporation of fossil taxa, will consider how latitudinal diversity gradients have changed through time, adding an important temporal component not often considered.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.