Evolution in deep-sea molluscs

深海是最多样化和最独特的海洋群落之一，其进化和历史发展几乎是未知的。这个研究项目将非常有助于回答在这个巨大的环境中进化多样化的两个最基本的问题：它在哪里发生，以及如何发生？它还将为未来的深海进化研究创造一个坚实的概念和方法背景。在这个项目中，研究人员开发了一个深海采样程序，以解决从他们之前的工作中出现的关于深海进化的三个主要假设。1)深度分化假说认为种群差异随深度的增加而减小。2) 3300 m处种群结构的断裂可能是未被认识到的系统地理屏障。3)深海种群可能是由于太稀少而无法成功交配而遭受慢性局部灭绝的水池，并通过从更丰富的深海种群不断迁移而得以维持。研究人员将使用深海原分支双壳类动物和多个独立的位点来测试这些假设。核位点作为种群结构、基因流动和历史影响的独立衡量标准是必不可少的，但对于确定我们所记录的一些显著差异是否代表隐物种也是至关重要的。该项目的主要重点是收集样本并从这些样本中开发核标记，这些样本在深海原分支中具有足够的变化，以测试每个假设并区分种内与种间变化。深海生物多样性源库假说是对深海物种多样性大尺度格局最综合、最全面的解释。如果通过对种群遗传结构的研究证明是正确的，将大大简化我们对物种多样性模式的进化和生态原因的理解。该研究项目的更广泛影响包括对本科生、研究生和公立学校教师的培训。马萨诸塞大学波士顿分校的学生和教师有很好的机会直接参与各级科学教育和公共宣传。生物系有美国国家科学基金会本科生研究经验和美国国家科学基金会本科生环境生物学指导补助金，面向代表性不足的少数民族。该校园拥有波士顿科学伙伴关系基金，用于升级高中科学课程，并设有海洋科学教育卓越中心，以培养公众对海洋科学的认识。该研究对深海生态系统的保护和可持续发展也具有广泛的意义。种群遗传结构是生物多样性的重要组成部分，对深海生物资源开发造成的物种灭绝具有重要意义。

The deep-sea supports one of the most diverse and unique marine communities, the evolutionary and historical development of which are virtually unknown. This research project will contribute very significantly to answering the two most basic questions about evolutionary diversification in this vast environment: Where does it occur, and how? It will also create a solid conceptual and methodological context for future evolutionary studies in the deep sea. In this project, the investigators have developed a deep-sea sampling program to address three main hypotheses about evolution in the deep sea that have emerged from their previous work. 1) The depth differentiation hypothesis suggesting population divergence decreases with depth. 2) The strong break in population structure at 3300 m may represent an unrecognized phylogeographic barrier. 3) Abyssal populations may be sinks that suffer chronic local extinction from being too rare to mate successfully, and are maintained by continued immigration from more abundant bathyal source populations. The investigators will test each of these hypotheses using deep-sea protobranch bivalves and multiple independent loci. Nuclear loci are essential as independent measures of population structure, gene flow and historical influences, but are also critical to establish whether some of the remarkable divergences we have documented represent cryptic species. The primary focus of this project is to collect the samples and develop nuclear markers from those samples that are sufficiently variable in deep-sea protobranchs to test each of the hypotheses and distinguish intra versus interspecific variation.The source-sink hypothesis of abyssal biodiversity is the most synthetic and comprehensive explanation of large-scale patterns of species diversity in the deep ocean. If proven correct by the proposed study of population genetic structure, it will greatly simplify our understanding of both evolutionary and ecological causes of species diversity patterns. Broader impacts of the research program include training for undergraduate and graduate students and public school teachers. UMass-Boston students and faculty have outstanding opportunities to be directly involved in science education and public outreach at all levels. The biology Department has NSF-Research Experiences for Undergraduate and NSF-Undergraduate Mentoring in Environmental Biology grants oriented toward underrepresented minorities. The campus has a Boston Science Partnership Grant to upgrade high school science curricula and a Center of Ocean Science Education Excellence to foster public awareness of ocean science. The research also has broad relevance for conservation and sustainable development of the deep-sea ecosystem. Genetic population structure is a crucial component of biodiversity, and has important implications for extinction potential from deep-sea exploitation.