Investigating the Fundamental Units of Natural Selection Amng Coral-Algal Symbioses: Ecological, Geographic, and Physiological Diversity of Host-Symbiont Genotypes

研究珊瑚-藻类共生体自然选择的基本单位：宿主-共生体基因型的生态、地理和生理多样性

• 批准号: 0928764
• 负责人: Todd LaJeunesse
• 金额: $ 61.28万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0928764&HistoricalAwards=false
• 关键词: Investigating; Fundamental; Units; Natural; Selection

Cnidarians and dinoflagellates in the genus Symbiodinium combine to form one of the most important symbioses on the planet. This project addresses both directly and indirectly several major fundamental gaps in our knowledge of coral-algal symbioses, and how these partnerships may respond to severe natural selection during periods of environmental disturbance, pollution, and climate change. Molecular genetic investigations conducted independently on the animal hosts and algal symbionts have enlightened our appreciation of their diversity. However, rarely have both partners been studied together in any detail. The realization that Symbiodinium populations in most coral colonies appear to be clonal means that genotype analyses can be conducted on both the animal and algal component of an intact association. Genotyping to the level of "individual" addresses questions of specificity and stability at the finest scale of genetic resolution and quantifies the diversity of "holobionts" at its most basic unit. Data acquired through genotyping are critical for deducing evolutionary processes between host and symbiont populations and how these partner combinations are potentially co-evolving in the face of climate change. Indeed these data will ultimately be used to parameterize evolutionary models of these symbioses with theoretical collaborators. Realizing the functional significance of natural diversity in all ecosystems is vital for understanding how life evolves and how it may respond evolutionarily to climate change over ecological time scales. This study will investigate the clonal diversity of Symbiodinium populations that associate with one of the most important Caribbean reef-building corals, Acropora palmata. This animal is highly specific for Symbiodinium, A3 despite the fact that its larvae must acquire symbionts from environmental pools. In recent work describing the population genetic structure of the A. palmata, thousands of samples were genotyped for the animal and then archived. These specimens provide an exceptional resource for intensive analyses of Symbiodinium genotype diversity within an individual colony, among separate colonies with the same animal genotype (ramets), among large stands of genetically unique colonies (genets), and across populations of A. palmate throughout much of its Caribbean distribution. Initial genotyping of 170 specimens based on four variable loci (4 to 8 more will be developed) indicates that each colony harbors a single dominant clone. This one-to-one host-symbiont genotype correspondence allows for direct comparison of host population genetic structure with that of the symbiont genetic structure to identify and then model how dispersal barriers and life history strategies influence the co-evolution of corals and dinoflagellates. Field collections, comparative physiological studies, and infection experiments will be conducted to investigate the ecological significance, specificity, and stability of diverse host populations with diverse populations of symbiont (Curacao) verses diverse host populations with a low diversity (few genotypes) of symbiont (US Virgin Islands), and finally low diversity host populations with low diversity symbiont populations (Florida). Significant geographic differences in the diversity of host-symbiont genotypic combinations mean that certain populations may be more responsive to natural selection than others.Determining the ecological and evolutionary processes that define the interactions between symbiotic corals is critical to our basic understanding of coral-algal symbioses and how these animal-microbe systems may respond to severe selection induced by climate change. Acropora palmata is particularly worthy of attention because it is one of two coral species currently listed as threatened under the US Endangered Species Act. By identifying the significance of symbiont diversity, conservation efforts can prioritize source populations for restoration material. This information is urgently needed as stated by the NOAA Acropora task force and results from this project will be made available regularly. The data generated here will serve prominent theoreticians to parameterize their evolutionary models of these symbioses and thus benefit the wider biological community and society at large. This study includes outreach missions to educate and train the public and public institutions. The ecological importance of coral-microbe interactions make them charismatic examples for teaching about the importance of microorganisms and symbioses to the health of the biosphere. Through continuing a series of workshops held since 2005 by SECORE (SExual Coral REproduction), the project will help build a cooperative international network of public aquariums and research institutions to establish coral breeding programs of A. palmata. This collaboration between scientists and specialists from large public aquaria and zoos located around the nation and world, serves to engage the public through the outreach mission of the zoos and thereby promotes understanding about the importance of coral symbioses and the basic process of science. Graduate and undergraduate students are an integral part of this project and will receive training in field and laboratory work and lecture courses.

刺胞动物和甲藻属的共生藻联合收割机形成了地球上最重要的共生体之一。该项目直接和间接地解决了我们对珊瑚藻类共生关系的认识中的几个主要的基本空白，以及这些伙伴关系如何在环境干扰，污染和气候变化期间应对严重的自然选择。对动物宿主和藻类共生体进行的分子遗传学研究启发了我们对其多样性的认识。然而，很少有两个合作伙伴一起研究的任何细节。大多数珊瑚群落中共生藻种群似乎是克隆的，这一认识意味着可以对完整协会的动物和藻类成分进行基因型分析。基因分型到“个体”的水平，解决了遗传分辨率最精细尺度上的特异性和稳定性问题，并量化了“全生物”最基本单位的多样性。通过基因分型获得的数据对于推断宿主和共生种群之间的进化过程以及这些伙伴组合在气候变化面前如何潜在地共同进化至关重要。事实上，这些数据最终将被用来与理论合作者参数化这些共生体的进化模型。认识到自然多样性在所有生态系统中的功能重要性，对于理解生命如何进化以及它如何在生态时间尺度上对气候变化作出进化反应至关重要。本研究将调查共生藻种群的克隆多样性，与加勒比海最重要的造礁珊瑚之一，鹿角珊瑚。这种动物是高度具体的共生藻，A3尽管事实上，它的幼虫必须获得共生体从环境池。在最近的工作中描述了A. palmata，数千个样本进行了基因分型的动物，然后存档。这些标本提供了一个特殊的资源，密集的分析共生藻基因型多样性在一个单独的殖民地，在不同的殖民地与相同的动物基因型（分株），在大的立场，遗传独特的殖民地（基因），并在整个人口的A。在加勒比海分布的大部分地区都是掌状的。基于4个可变基因座对170个样本进行的初始基因分型（将开发4至8个）表明，每个菌落都含有一个单一的显性克隆。这种一对一的主机共生体基因型对应允许直接比较宿主种群的遗传结构与共生体的遗传结构，以确定，然后模拟扩散障碍和生活史策略如何影响珊瑚和甲藻的共同进化。将进行田间采集、比较生理学研究和感染实验，以调查具有不同共生体种群的不同宿主种群（库拉考）与具有低多样性（少数基因型）共生体的不同宿主种群（美属维尔京群岛）以及具有低多样性共生体种群的低多样性宿主种群（佛罗里达）的生态学意义、特异性和稳定性。宿主-共生体基因型组合多样性的显著地理差异意味着某些种群可能比其他种群对自然选择更敏感，确定共生珊瑚之间相互作用的生态和进化过程对于我们对珊瑚-藻类共生的基本理解至关重要，以及这些动物-微生物系统如何应对气候变化引起的严重选择。Acropora palmata特别值得关注，因为它是目前根据美国濒危物种法案被列为受威胁的两种珊瑚物种之一。通过确定共生体多样性的重要性，保护工作可以优先考虑恢复材料的来源种群。正如海洋大气署Acropora工作队所指出的那样，迫切需要这一信息，该项目的结果将定期公布。这里生成的数据将为杰出的理论家提供服务，以参数化这些共生体的进化模型，从而使更广泛的生物群落和整个社会受益。这项研究包括对公众和公共机构进行教育和培训的外联工作。珊瑚-微生物相互作用的生态重要性使它们成为教授微生物和共生体对生物圈健康的重要性的迷人例子。通过SECORE（性珊瑚繁殖）自2005年以来举办的一系列研讨会，该项目将帮助建立一个公共水族馆和研究机构的国际合作网络，以建立A.掌形的来自全国和世界各地的大型公共水族馆和动物园的科学家和专家之间的这种合作，有助于通过动物园的外展使命吸引公众，从而促进对珊瑚共生的重要性和科学的基本过程的理解。研究生和本科生是这个项目的一个组成部分，将接受实地和实验室工作和讲座课程的培训。