Barriers to cross-shelf coral connectivity in the Florida Keys

佛罗里达群岛的珊瑚礁严重衰退，这是沿着最突出的珊瑚礁，而许多近岸珊瑚礁保留了高珊瑚覆盖率。那么，为什么从幸存的近岸斑块中产生的珊瑚幼虫不会使近海珊瑚礁退化呢？研究人员假设，这种跨大陆架的移民不能在新的栖息地生存，这是由于不同环境条件下的遗传专业化，具体到他们的起源珊瑚礁。该项目将分析珊瑚种群的遗传多样性，以量化三种常见珊瑚物种中这一障碍的严重程度。这将是第一项评估珊瑚在整个海景中扩散的生态障碍强度的研究，这将填补一个重要的知识空白，目前无法对佛罗里达珊瑚礁的威胁进行知情评估，并开发准确的模型来预测其未来。该项目包括各种影响范围更广的活动。公众宣传：该项目已做好充分准备，以提高公众对持续的生物多样性丧失的认识。研究人员定期在奥斯汀的不同场所进行公开讲座，如星空下的科学，酒吧里的科学和书呆子之夜。该项目的进展情况将通过新闻稿、得克萨斯大学公共宣传网页“知道”和《得克萨斯人日报》上的材料予以跟踪。K-12推广：两名实习生从克罗克特高中，并将参与研究。研究生教育：该项目将是一个全日制研究生的主要博士主题。本科教育：主要研究者定期雇用本科生。在这个项目中，他们将参与现场实验和样品处理，然后分配个人的子项目。 促进快速数据共享：所有测序数据将在出版前无条件使用。具体来说，研究人员将快速分享新的珊瑚基因组数据以及珊瑚种群全基因组变异的数据。该项目由四个部分组成，每个部分都旨在展示近岸和近海珊瑚礁之间的差异选择行为，并获得量化估计其人口影响。(1)寻找在近海和近海栖息地之间进行选择的基因组特征。该研究小组将对三种代表不同生活史的珊瑚物种进行全基因组基因分型，并沿佛罗里达珊瑚礁区沿着复制近岸-近海种群比较。(2)通过比较幼鱼和成鱼的近岸-近海分化程度，确认选择的连续作用。据推测，青少年经历本地选择的时间较短，因此在候选基因座上应该表现出较少的跨货架分歧。(3)通过量化基因型青少年的原位生长和存活来证明候选基因座的基因型与当地适合度的关联。这一部分以及第2部分预计将提供对跨货架移民的选择强度的定量估计。(4)通过模拟趋异选择下的基因组进化来验证所获得的估计值，并确认所提出的选择方案与观察到的基因组特征是相容的。

Coral reefs in the Florida Keys are in severe decline, which is the most prominent along the offshore reef tract while many nearshore reefs retain high coral cover. Why then coral larvae produced from surviving nearshore patches do not recolonize offshore reefs? The investigators hypothesize that such cross-shelf migrants do not survive in the new habitat due to genetic specialization for different environmental conditions, specific to their reef of origin. This project will analyze genetic diversity of coral populations to quantify the severity of this barrier in three common coral species. This will be the first study to assess the strength of ecological barriers to coral dispersal across the seascape, which will fill an important knowledge gap that currently precludes informed assessment of threats to Florida reefs and development of accurate models to forecast their future. The project includes a variety of broader impact activities. Public outreach: This project is very well poised to raise public awareness of ongoing biodiversity loss. The investigators regularly give public lectures at diverse Austin venues, such as Science Under the Stars, Science in the Pub, and Nerd Nite. The progress of the project will be followed by press releases, materials on the University of Texas public outreach web page Know and in The Daily Texan. K-12 outreach: Two interns from Crockett High School and will be involved in the research. Graduate education: The project will be the main PhD theme for one full-time graduate student. Undergraduate education: The primary investigator regularly employs undergraduates. In this project they will participate in field experiments and sample processing, and later assigned individual sub-projects. Promotion of rapid data sharing: All sequencing data will be made available for unconditional use prior to publication. Specifically, the investigators will rapidly share new coral genome data, as well as data on genome-wide variation in coral populations.The project consists of four parts, each of which is designed to demonstrate the action of divergent selection among nearshore and offshore reefs and to obtain quantitative estimate of its demographic impact. (1) To look for genomic signatures of ongoing selection between inshore and offshore habitats. The research team will perform genome-wide genotyping in three coral species representing alternative life histories and replicate the nearshore-offshore population comparison along the Florida Reef Tract. (2) To confirm continuous action of selection by comparing the extent of inshore-offshore divergence among juveniles and adults. Juveniles are presumed to have experienced local selection for shorter time and hence should show less cross-shelf divergence at the candidate loci. (3) To demonstrate association of genotypes at the candidate loci with local fitness by quantifying in situ growth and survival of genotyped juveniles. This part as well as part 2 is expected to provide quantitative estimates of the strength of selection against cross-shelf immigrants. (4) To verify the obtained estimates by simulating genome evolution under divergent selection and confirming that the proposed selection scenario is compatible with the observed genomic signatures.