Collaborative Research: Evolution of Population Connectivity in Sea Stars

Drs。Toonen和Grosberg将研究在世界各地温带和热带浅海中发现的海星（Asterinidae，或蝙蝠星）的种群遗传变异和繁殖。海洋种群遗传变异在很大程度上被解释为散布差异：种群间强烈的遗传漂变，局部近亲繁殖，频繁的局部灭绝，以及没有浮游生物幼虫的物种的局部适应潜力；基因流动强，遗传漂变少，近亲繁殖有限，幼虫广泛传播的物种形成或灭绝的机会较少。然而，最近在各种生物和海洋中使用不同遗传标记的研究表明，这种观点是有限的。除在洋流中扩散外，其他过程可能对种群遗传结构有主要影响。在扩散、基因流动、突变和遗传漂变之间，许多物种可能无法达到种群遗传平衡。本研究将有助于验证这些期望，并通过以下方式扩展海洋种群遗传变异的观点：(1)使用多个基因比较不同蝙蝠星系和生命周期改变的物种的种群结构；(2)评估其他生命周期差异（特别是自交和内受精）对种群遗传模式的贡献；(3)利用已知的物种间系统发育关系，探究生命周期特征趋同进化导致相似种群遗传模式的频率；(4)评估地理范围扩大、气候变化或近期物种形成事件等历史过程对种群遗传模式的贡献，这些历史过程可能使种群遗传模式偏离基于扩散潜力的预期模式；(5)估计基因流动和种群结构对配子间（受精时）或基因组间（幼虫发育时）生殖不亲和进化的影响。调查人员和他们的学生将加入一个由加拿大和澳大利亚研究人员组成的既定合作项目。来自所有四个机构的女性、夏威夷原住民和澳大利亚土著学生研究人员将在不同的领域（阿拉斯加、不列颠哥伦比亚省、加利福尼亚、巴哈、昆士兰、新南威尔士州）和实验室环境中工作。这些学生将发展分子遗传学、定量分析、系统发育学和生殖生物学的综合技能。如果以前的研究有任何指导意义的话，这些结果很可能通过识别新的隐藏物种，为海洋生物多样性的基础知识做出贡献。比较种群遗传分析将帮助海洋生态学家和保护生物学家了解影响种群结构和当地遗传多样性的各种因素。这些知识对于诸如加利福尼亚海洋保护区的位置和管理、受沿海开发和有害入侵物种威胁的澳大利亚一些濒危小行星的保护状况以及已被赋予保护地位等问题至关重要；以及夏洛特女王群岛拟议中的瓜伊哈纳斯世界遗产中海洋生物的独特遗传特性。

Drs. Toonen and Grosberg will study population genetic variation and reproduction in sea stars (Asterinidae, or bat stars) found in shallow temperate and tropical oceans around the world. Marine population genetic variation has largely been interpreted in terms of dispersal differences: strong genetic drift among populations, local inbreeding, frequent local extinction, and potential for local adaptation in species without planktonic larvae; strong gene flow, little genetic drift, limited inbreeding, and fewer opportunities for speciation or extinction in species with widespread larval dispersal. However, recent studies in various organisms and oceans using diverse genetic markers suggest that this view is limited. Processes other than dispersal in ocean currents may have a predominant influence on population genetic structure. Many species may not be expected to approach population genetic equilibrium between dispersal, gene flow, mutation, and genetic drift. This research will help to test these expectations and expand the view of population genetic variation in the ocean by (1) comparing population structure using multiple genes for different bat star lineages and species with modified life cycles; (2) assessing the contribution of other life cycle differences (especially selfing and internal fertilization) to population genetic patterns; (3) using known phylogenetic relationships among species to ask how often convergent evolution of life cycle traits has resulted in similar population genetic patterns; (4) evaluating the contribution of historical processes such as geographical range expansion, climate change, or recent speciation events that could push population genetic patterns away from expected patterns based on dispersal potential; (5) estimating the impact of gene flow and population structure on the evolution of reproductive incompatibility between gametes (at fertilization) or between genomes (during larval development). The investigators and their students will join an established collaboration involving Canadian and Australian researchers. Female, native Hawaiian, and Australian Aboriginal student researchers from all four institutions will work in diverse field (Alaska, British Columbia, California, Baja, Queensland, New South Wales) and lab settings. These students will develop a combination of skills in molecular genetics, quantitative analysis, phylogenetics, and reproductive biology. If previous studies are any guide, the results are likely to contribute to basic knowledge of biological diversity in the ocean by identifying new cryptic species. The comparative population genetic analysis will help marine ecologists and conservation biologists understand the mix of factors that contribute to population structure and local genetic diversity. Such knowledge is crucial to issues such as the location and management of marine protected areas in California, the conservation status of some endangered Australian asterinids that are threatened by coastal development and noxious invasive species and have been given protected status; and the unique genetic properties of the marine organisms in the proposed Gwaii Haanas World Heritage Site in the Queen Charlotte Islands.