Assessment of Population Connectivity in Caribbean Reef Fishes Using Microsatellite Loci

本研究项目的重点是解决关于珊瑚礁鱼类幼鱼长距离扩散与非常局部扩散的重要性的激烈辩论。大多数珊瑚礁鱼类和无脊椎动物在相对静止的幼鱼和成鱼阶段之前有一个分散的幼虫阶段。了解幼虫扩散的空间尺度是理解种群连通性的基础。大多数较早的研究表明，广泛的分散是主要的力量，所以所有的种群都是紧密相连的。然而，最近的一些研究表明，海洋学的细节和幼虫的行为如何结合起来，有利于非常有限的扩散。目前的研究项目旨在通过检测种群之间的遗传分化来显示在什么空间尺度上发生扩散。除了解决这一持续的争议之外，这项活动还将通过帮助确定指定保护区域的珊瑚礁鱼类的来源和汇来帮助设计海洋保护区。它也可用于其他保护目的，例如在加勒比和其他地方，即使在没有保护区的情况下，对珊瑚礁鱼类的单独管理种群的定义。通过选择采样地点、焦点物种和实验设计中的遗传方法，最大限度地提高了检测种群分化的可能性，从而扩大了扩散规模。采样点按等级排列，在较大区域（岛屿）内的小地点（珊瑚礁）在区域（由大规模洋流连接的岛屿群）内。这三种研究物种在可能分散的幼虫阶段的持续时间不同：从蓝头濑鱼的长远洋幼虫持续时间到蓝条纹鲈的短。遗传分析将包括在微卫星位点对个体进行基因分型。这些基因座已经被证明可以检测到鱼类种群之间的细微差异，而其他方法都失败了。基因型数据的分析将显示在什么空间尺度上种群分化，珊瑚礁，岛屿，或区域，表明幼虫扩散的规模。物种间结果的比较将表明结果的普遍性，或者它们对生活史特征的依赖性。

This research project focuses on resolving the vigorous debate over the importance of long distance dispersal versus very local dispersal of larval reef fishes. Most coral reef fish and invertebrates have a dispersive larval stage preceding a relatively sedentary juvenile and adult stage. Understanding the spatial scale at which larval dispersal operates is fundamental to understanding the connectedness of populations. Most older work suggests that wide dispersal is the dominant force, so all populations are well connected. Some recent work however, shows how oceanographic details and larval behavior may combine to favor very limited dispersal. The present research project is designed to show at what spatial scale dispersal is occurring by detecting genetic differentiation among populations. In addition to resolving this ongoing controversy, this activity will aid in the design of marine reserves by helping to identify sources and sinks of reef fish species in areas slated for protection. It may also be useful for other conservation purposes, such as the definition of separate management stocks of coral reef fish in the Caribbean and elsewhere, even in the absence of reservesThrough choice of sampling sites, focal species, and genetic approach in experimental design, the likelihood of detecting population differentiation and therefore scale of dispersal has been maximized. Sampling sites have been arranged hierarchically, small sites (reefs) within larger areas (islands) within regions (groups of islands linked by large-scale currents). The three study species differ in duration of the larval stage likely to disperse: from long pelagic larval duration in bluehead wrasse to short in blue-striped grunts. Genetic analyses will involve genotyping individuals at microsatellite loci. These loci have been shown to detect subtle differentiation among fish populations where other approaches have failed. Analysis of genotype data will show at what spatial scale populations are differentiated, reef, island, or region, indicating the scale of larval dispersal. Comparison of results among species will indicate the generality of results, or their dependence of life history traits.