Reproductive and Geographic Evidence for Source-Sink Dynamics in Deep-Sea Benthic Communities

深海底栖群落源汇动力学的生殖和地理证据

• 批准号: 1129612
• 负责人: Michael Rex
• 金额: $ 14.56万
• 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 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129612&HistoricalAwards=false
• 关键词: Reproductive; Geographic; Evidence; Source; Sink

Many hypotheses have been proposed to explain deep-sea species diversity including competition, predation, physical disturbance, patch mosaics, coarse-grained environmental heterogeneity, metapopulation dynamics mediated by dispersal, and a host of abiotic factors. Evidence supporting these ideas comes largely from spatio-temporal patterns of alpha- (local) diversity. This investigator and collaborators proposed an alternative explanation based on species depth ranges. Abyssal populations of mollusks do not comprise a unique assemblage, but are mainly deeper attenuated range extensions of bathyal populations. Densities of many abyssal populations are so extraordinarily low, especially for minute organisms with low mobility and separate sexes, that it is implausible they could be reproductively viable. Most have larval dispersal ability. This suggested that many abyssal populations are maintained by source-sink dynamics. They suffer chronic local extinction from vulnerabilities to Allee effects, and persist through continued immigration from more abundant bathyal source populations. Source-sink dynamics provides a broad synthetic framework within which other potential causes of diversity (above) can act. It also resolves the long-standing paradox of how abyssal diversity could be shaped by interactions when density is so low. The theory does not require that abyssal communities be ecologically structured. They may be mostly a passive consequence of dispersal.This project will apply two tests for source-sink dynamics: 1. The investigators will perform a direct test by examining reproductive patterns in molluscan species whose bathymetric ranges span the lower bathyal zone and the abyss. Since rare abyssal populations are predicted not to be reproductively viable, they should show diminished gamete production, and no evidence of mating. 2. They will conduct an extensive new synthesis of geographic evidence for source-sink dynamics. Geographic patterns, are currently the primary evidence available on very large spatial scales, and are invaluable for identifying taxonomic and geographical scenarios for future reproductive studies. Recent advances in nested analysis allow us to determine statistically whether abyssal communities are nested subsets of bathyal communities as predicted by source-sink theory. Newly available large datasets include Pan Atlantic distributions of gastropods, bivalves, and cumaceans from the Woods Hole Oceanographic Institution's Benthic Sampling Program; mollusks, asteroids and holothurians from Southampton Oceanography Centre's sampling program in the Porcupine Seabight and Abyssal Plains, and macrofaunal taxa from Texas A&M's Deep Gulf of Mexico Benthic Program. The investigator makes specific predictions about which groups should show geographic evidence of source-sink dynamics based on their natural history and the productivity regime. This synthesis will also contribute significantly to documenting and understanding beta diversity, the most important remaining challenge in deep-sea community ecology.Intellectual Merit. The source-sink hypothesis has the potential to unify and synthesize the large number of disparate theories of community structure in the deep-sea benthos. The research will also dramatically increase the number of computerized datasets on biogeographic distributions. The single greatest obstacle to expanding our understanding of macroecology in the deep sea is the near absence of data on species ranges. This also has vital implications for conservation and sustainable development of the deep-sea ecosystem. Without much more information on geographic ranges, it is currently impossible to gauge the extinction potential of deep-sea species.Broader Impacts. 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 Experience for Undergraduates Grant, an NIH-Initiative to Maximize Student Diversity Grant, and a NIH-Bridges to Baccalaureate Grant (with Bunker Hill and Roxbury Community Colleges). The campus has an NSF GK-12 Watershed Integrated Science Partnership 2(WISP2) Grant to upgrade high school science curricula, a McNair Grant, and a Lewis Stokes Alliances for Minority Participation Grant, all oriented toward assisting underrepresented minorities. Undergraduates, graduate students and teachers will be recruited into this research program, and topics in deep-sea biology will be incorporated into university and high school curricula.

人们提出了许多假说来解释深海物种多样性，包括竞争、捕食、物理干扰、斑块镶嵌、粗粒环境异质性、扩散介导的集合种群动态以及许多非生物因素。支持这些观点的证据主要来自阿尔法（本地）多样性的时空模式。这位研究者和合作者提出了一种基于物种深度范围的替代解释。软体动物的深海种群不包括一个独特的组合，但主要是更深的半深海种群的衰减范围的延伸。许多深海种群的密度非常低，特别是那些流动性低、性别分离的微小生物，它们不可能有繁殖能力。多数具有幼虫扩散能力。这表明，许多深海种群是由源-汇动态维持的。他们遭受慢性局部灭绝的脆弱性，以Allee效应，并坚持通过继续移民从更丰富的半深海源人口。源-汇动态提供了一个广泛的综合框架，多样性的其他潜在原因（见上文）可在此框架内发挥作用。它还解决了一个长期存在的悖论，即在密度如此之低的情况下，深海多样性是如何通过相互作用形成的。这一理论并不要求深海生物群落具有生态结构。本计画将应用两项源-汇动态测试：1。调查人员将进行直接测试，检查水深范围跨越下半深海带和深海的软体动物物种的繁殖模式。由于罕见的深海种群被预测没有生殖能力，它们应该显示出减少的配子生产，没有交配的证据。2.他们将对源-汇动态的地理证据进行广泛的新综合。地理模式，目前在非常大的空间尺度上提供的主要证据，是非常宝贵的，为未来的生殖研究确定分类和地理情景。嵌套分析的最新进展，使我们能够确定统计是否深海社区嵌套亚组的半深海社区的预测源-汇理论。新获得的大型数据集包括来自伍兹霍尔海洋研究所底栖采样计划的腹足类、双壳类和库马类的泛大西洋分布;来自南安普顿海洋学中心豪猪湾和深海平原采样计划的软体动物、小行星和海参类，以及来自德克萨斯A M公司墨西哥湾深海底栖计划的大型底栖动物分类群。研究人员作出具体的预测，哪些群体应该显示源汇动态的地理证据的基础上，他们的自然历史和生产力制度。这一综合报告还将大大有助于记录和了解β多样性，而β多样性是深海群落生态学中最重要的剩余挑战。源-汇假说有可能统一和综合关于深海底栖生物群落结构的大量不同理论。这项研究还将大大增加关于地理分布的计算机化数据集的数量。扩大我们对深海宏观生态学的理解的最大障碍是几乎缺乏关于物种范围的数据。这也对深海生态系统的养护和可持续发展产生重大影响。如果没有更多关于地理范围的信息，目前就不可能衡量深海物种的灭绝潜力。在麻省大学波士顿分校，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。目前，生物系有一个NSF研究经验的本科生补助金，一个NIH倡议，以最大限度地提高学生的多样性补助金，和一个NIH桥梁学士学位补助金（与掩体山和罗克斯伯里社区学院）。校园有一个NSF GK-12流域综合科学伙伴关系2（WISP 2）赠款，以升级高中科学课程，麦克奈尔赠款，和刘易斯斯托克斯联盟少数民族参与赠款，所有面向帮助代表性不足的少数民族。将招募本科生、研究生和教师参加这一研究方案，深海生物学专题将纳入大学和高中课程。