Collaborative Research: Evolution of Population Connectivity in Sea Stars

Toonen博士和Grosberg博士将研究世界各地浅温带和热带海洋中发现的海星(Asterinidae，或蝙蝠星)的种群遗传变异和繁殖。海洋种群的遗传变异在很大程度上被解释为扩散差异：种群间的遗传漂移强烈，局部近亲繁殖，局部灭绝频繁，没有浮游幼虫的物种具有局部适应的潜力；在幼虫广泛扩散的物种中，基因流动强烈，遗传漂移很小，近亲繁殖有限，物种形成或灭绝的机会较少。然而，最近使用不同遗传标记对各种生物和海洋进行的研究表明，这种观点是有限的。洋流中除扩散以外的其他过程可能对种群遗传结构产生主要影响。许多物种可能无法在扩散、基因流动、突变和遗传漂移之间达到种群遗传平衡。这项研究将有助于检验这些预期，并通过以下方式扩大海洋种群遗传变异的观点：(1)比较不同蝙蝠星族和具有改变生活周期的物种使用多个基因的种群结构；(2)评估其他生命周期差异(特别是自交和内部受精)对种群遗传模式的贡献；(3)利用物种之间已知的系统发育关系，询问生命周期特征的趋同进化导致相似种群遗传模式的频率；(4)评估历史过程的贡献，如地理范围扩大、气候变化或最近的物种形成事件，这些过程可能会推动种群遗传模式偏离基于扩散潜力的预期模式；(5)估计基因流和种群结构对配子间(受精时)或基因组间(幼虫发育期间)生殖不亲和性进化的影响。研究人员和他们的学生将加入由加拿大和澳大利亚研究人员参与的既定合作。来自所有四个机构的女性、夏威夷原住民和澳大利亚原住民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、加利福尼亚州、巴哈、昆士兰、新南威尔士州)和实验室工作。这些学生将发展分子遗传学、定量分析、系统发育和生殖生物学方面的综合技能。如果以前的研究有任何指导意义的话，那么这些结果很可能有助于识别新的神秘物种，从而有助于了解海洋生物多样性的基本知识。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导致种群结构和当地遗传多样性的各种因素的组合。这些知识对于以下问题至关重要：加利福尼亚州海洋保护区的位置和管理；受到沿海开发和有害入侵物种威胁并已获得保护地位的一些濒危澳大利亚小行星的保护状况；以及拟议中的夏洛特女王群岛夏威夷世界遗产地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.