Evolution of Deep Sea Molluscs II

深海软体动物的进化II

• 批准号: 1130541
• 负责人: Ron Etter
• 金额: $ 30.03万
• 依托单位: University of Massachusetts Boston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1130541&HistoricalAwards=false
• 关键词: Evolution; Deep; Sea; Molluscs; II

The first explicit model of population differentiation and speciation in the deep-sea fauna, the depth-differentiation hypothesis, was formulated in the early 1990s. According to this theory, the potential for population differentiation decreases with depth because the bathyal zone (200- 4000 m) has stronger selective gradients and more opportunity for geographic isolation to impede gene flow than does the more extensive and environmentally uniform abyssal plain (4000 m). To determine whether depth-related variation is genetic, and therefore a consequence of evolutionary change, the PI has developed new methods to extract and sequence mitochondrial DNA from archived deep-sea molluscan species collected in earlier expeditions that had been fixed in formalin and preserved in alcohol. These preliminary studies supported the depth-differentiation hypothesis. They also revealed the limitations of using preserved material. For this project, the PI describes 2 hypotheses about evolution in the deep sea that emerged from the previous work: 1) The depth differentiation hypothesis suggests population divergence decreases with depth; and 2) A strong break in population structure at 3300 m might represent an unrecognized phylogeographic barrier. The PI will test each of these hypotheses with multiple independent loci using deep-sea protobranch bivalves and recently developed statistical phylogeographic and phylogenetic models. The aforementioned work relied on formalin-fixed tissues, restricting analyses to a single locus (mtDNA). 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 the PI documented represent cryptic species. The new material collected during the previous round of funding allowed the PI to develop the necessary nuclear loci and assess their utility for this work. The primary focus of this proposal is to use these new markers to test each of these hypotheses and distinguish intra- versus inter-specific variation. Intellectual Merit: The deep-sea supports one of the most diverse and unique marine communities, the evolutionary and historical development of which is virtually unknown. The proposed research will contribute very significantly to answering the two most basic questions about evolutionary diversification in this vast and remote environment: Where does it occur, and how? Analysis of the strong bathymetric divergence in Deminucula atacellana will provide the first detailed investigation of potential incipient speciation in a deep-sea organism (apart from reducing environments) and possibly identify the scales and mechanisms involved. It will also create a solid conceptual and methodological context for future evolutionary studies in the deep sea and lay the groundwork for understanding bathymetric and geographic variation at much larger scales (e.g., among ocean basins or pan-Atlantic). Broader Impacts: The research program will train undergraduate and graduate students and public school teachers. At UMass-Boston, students and faculty have outstanding opportunities to be directly involved in science education and public outreach at all levels. Currently, the biology Department has an NSF-Research Experiences for Undergraduate program, an NIH Initiative for Maximizing Student Diversity (IMSD) Program, a Bridges to Baccalaureate Program, and an NSF Undergraduate Mentoring in Environmental Biology program. All are oriented toward underrepresented minorities, and students from each of these initiatives have and will continue to be been involved in the PI's research. The campus has a Boston Science Partnership Grant to upgrade high school science curricula and is a Center of Ocean Science Education Excellence to foster public awareness of ocean science. The PI will recruit undergraduates, graduate students, and teachers into this research program, and topics in deep-sea biology will be incorporated into university and high school curricula. 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.

深海动物群种群分化和物种形成的第一个明确模型，即深度分化假说，于 20 世纪 90 年代初提出。根据这一理论，种群分化的潜力随着深度的增加而降低，因为深海带（200-4000米）比更广泛和环境均匀的深海平原（4000米）具有更强的选择梯度和更多的地理隔离机会来阻碍基因流动。为了确定与深度相关的变异是否是遗传性的，从而确定是进化变化的结果，PI开发了新方法，从早期探险中收集的存档深海软体动物物种中提取线粒体DNA并进行测序，这些物种已在福尔马林中固定并保存在酒精中。这些初步研究支持了深度分化假说。他们还揭示了使用保存材料的局限性。对于这个项目，PI 描述了先前工作中出现的关于深海进化的 2 个假设： 1）深度分化假说表明种群分化随着深度而减小； 2）3300米处种群结构的强烈突破可能代表着一个未被认识到的系统发育地理障碍。 PI 将使用深海原分支双壳类动物和最近开发的统计系统发育和系统发育模型，通过多个独立位点测试每个假设。上述工作依赖于福尔马林固定的组织，将分析限制在单个基因座（mtDNA）。核位点对于种群结构、基因流动和历史影响的独立测量至关重要，而且对于确定 PI 记录的一些显着差异是否代表神秘物种也至关重要。上一轮资助期间收集的新材料使 PI 能够开发必要的核位点并评估其对这项工作的效用。该提案的主要重点是使用这些新标记来测试每个假设并区分种内变异和种间变异。智力优势：深海支持着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。拟议的研究将非常有助于回答关于这个广阔而偏远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？对 Deminucula atacellana 强烈的水深差异的分析将首次详细研究深海生物体中潜在的早期物种形成（除了还原性环境），并可能确定所涉及的规模和机制。它还将为未来的深海进化研究创造坚实的概念和方法论背景，并为理解更大范围内的水深和地理变化（例如，大洋盆地或泛大西洋之间）奠定基础。更广泛的影响：该研究计划将培训本科生、研究生以及公立学校教师。在麻省大学波士顿分校，学生和教师拥有直接参与各级科学教育和公共宣传的绝佳机会。目前，生物系拥有 NSF 本科生研究经验项目、NIH 学生多样性最大化计划 (IMSD)、学士学位桥梁项目和 NSF 环境生物学本科生辅导项目。 所有项目均面向代表性不足的少数群体，这些项目的学生已经并将继续参与 PI 的研究。该校园拥有波士顿科学合作伙伴补助金，用于升级高中科学课程，并且是一个海洋科学教育卓越中心，旨在培养公众对海洋科学的认识。 PI将招募本科生、研究生和教师参与该研究项目，深海生物学主题将纳入大学和高中课程。该研究还与深海生态系统的保护和可持续发展具有广泛的相关性。遗传种群结构是生物多样性的重要组成部分，对深海开发造成的灭绝潜力具有重要影响。