RUI: Ecology and Evolution of Range Limits in Intertidal Organisms

RUI：潮间带生物范围限制的生态学和进化

• 批准号: 0648606
• 负责人: Patrick Krug
• 金额: --
• 依托单位: California State L A University Auxiliary Services Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0648606&HistoricalAwards=false
• 关键词: RUI; Ecology; Evolution; Range; Limits

Range limits of marine and terrestrial taxa are shifting dramatically in response to global climate change, but predicting range shifts requires a mechanistic understanding of factors that limit distributions. Causal determinants of range limits remain largely unknown for intertidal animals, despite the fact that many invertebrates have rapidly changing ranges. An improved understanding of range limits is fundamentally important to marine ecology and evolutionary biology, and is necessary to predict the ecological impacts of ongoing climate change.Intellectual merits: The principal investigator will identify range-limiting factors for Alderia spp., intertidal sea slugs that are excellent models for understanding the effects of climate change. A molecular genetic study by the PI and colleagues showed A. modesta occurs north of San Francisco (SF), but a cryptic sister species with variable development (described as A. willowi) occurs south of SF. Advantages to this system include: (1) Alderia spp. are strictly intertidal, with no subtidal refuge from high temperature; (2) their linear ranges are easy to characterize spatially and temporally, and have shifted in the past 50 years; (3) the sister species consistently occur at different times of the year in SF Bay, suggesting that trade-offs in temperature and salinity tolerance define their niches; (4) host-dependency may affect ranges of these specialized herbivores, as predicted by modeling; (5) larval supply to edge populations can be quantified for each species using a genetic method for identifying larvae; and (6) A. willowi has a 3-week generation time in lab culture, making it ideal for artificial selection experiments. The research will focus on 3 questions: (A) What features of the physical or biological environment limit a species to its current range? Field surveys will correlate adult and larval abundance with environmental parameters, and lab experiments will test salinity and temperature thresholds for both adults and larvae. Host-dependent larval settlement and adult fitness will also be tested to determine if Alderia spp. are adapted to regional strains of their host alga. (B) What factors drive metapopulation dynamics at range edges? Larval supply to edge habitats will be quantified using species-specific primers and multiplex PCR to differentiate larvae of Alderia spp. from monthly plankton tows. Lab studies will test whether the mating system of Alderia allows either species, when abundant, to inhibit colonization by its congener via Allee effects. (C) What inhibits adaptation to environmental thresholds that set range limits? Artificial selection experiments will estimate (1) extant genetic variation in edge vs. center populations of A. willowi for key traits, and (2) trade-offs between heat and salinity tolerance, reproduction and growth after 36 generations of selection, both issues of fundamental evolutionary importance.Broader impacts: This project will elucidate the ecological and genetic basis for range limits in two common gastropods, providing insight into general mechanisms that may set borders in other intertidal taxa. Such data are critical for predicting biological response to climate change. Funding will allow a young PI to build on prior support, integrating molecular and larval ecology with organismal biology. Student training is a major thrust of this proposal, which will provide new research opportunities at CSULA, a Hispanic-serving institution. One undergraduate and two masters students will be supported each year, likely ethnic minorities; the PI recruits from under-represented groups, and 3 of 5 current students are Latino. The PI has published with both undergraduate and graduate students, and three former students entered Ph.D. programs in the last 2 years. Through established partnerships with area high school teachers, the PI and all students will give research talks to biology classes, lead field trips, and 1-2 high school seniors per year will perform research projects in the PI's lab; these activities enhance outreach to minority groups while educating local students about human impacts on the coastal environment.

随着全球气候变化，海洋和陆地分类群的分布范围正在急剧变化，但预测范围变化需要对限制分布的因素有一个机制上的理解。尽管许多无脊椎动物的活动范围在迅速变化，但潮间带动物活动范围限制的决定因素在很大程度上仍然未知。提高对范围限制的了解对海洋生态学和进化生物学至关重要，并且对预测持续气候变化的生态影响是必要的。智力优势：首席研究员将确定潮间带海蛞蝓Alderia spp.的范围限制因素，它是理解气候变化影响的优秀模型。PI及其同事进行的一项分子遗传学研究表明，A. modesa发生在旧金山（SF）的北部，但一种发育不完全的隐蔽姊妹种（被称为A. willowi）发生在旧金山以南。该系统的优点包括：(1)桤木属属严格意义上的潮间带，没有躲避高温的潮下避难所；(2)近50 a来，其线性变化范围具有明显的时空特征；(3)姐妹种在一年中的不同时间出现，表明耐温性和耐盐性的权衡决定了它们的生态位；(4)根据模型预测，寄主依赖性可能影响这些特殊食草动物的分布范围；(5)利用鉴定幼虫的遗传方法，可以量化每个物种边缘种群的幼虫供应；(6)杨柳在实验室培养的世代时间为3周，适合进行人工选择实验。研究将集中在3个问题上：(A)物理或生物环境的哪些特征限制了一个物种的生存范围？实地调查将把成虫和幼虫的丰度与环境参数联系起来，实验室实验将测试成虫和幼虫的盐度和温度阈值。寄主依赖性的幼虫沉降和成虫适应性也将被测试，以确定桤木藻是否适应其寄主藻类的区域菌株。(B)疆域边缘的超种群动态驱动因素是什么？利用物种特异性引物和多重PCR将Alderia sp .幼虫与每月浮游生物群落区分开来，定量分析边缘生境的幼虫供应。实验室研究将测试桤木属的交配系统是否允许任何一种物种在数量丰富时，通过Allee效应抑制其同系物的定植。(C)是什么阻碍了对设定范围限制的环境阈值的适应？人工选择实验将评估：(1)杨柳边缘种群与中心种群在关键性状上的遗传变异；(2)36代选择后耐热和耐盐性、繁殖和生长之间的权衡，这两个问题都具有基本的进化重要性。更广泛的影响：该项目将阐明两种常见腹足类动物范围限制的生态和遗传基础，为其他潮间带类群设定边界的一般机制提供见解。这些数据对于预测生物对气候变化的反应至关重要。资金将允许年轻的PI在先前支持的基础上，将分子和幼虫生态学与有机生物学结合起来。学生培训是该提案的主要推动力，这将为CSULA提供新的研究机会，这是一个为西班牙裔服务的机构。每年将资助一名本科生和两名硕士生，可能是少数民族；PI从代表性不足的群体中招收学生，目前的学生中有五分之三是拉丁裔。PI在本科生和研究生中都有出版，在过去的两年里，有三位以前的学生进入了博士课程。通过与当地高中教师建立伙伴关系，PI和所有学生将在生物课上进行研究演讲，带领实地考察，每年有1-2名高中毕业生将在PI的实验室进行研究项目；这些活动加强了与少数群体的联系，同时教育当地学生了解人类对沿海环境的影响。