Mitochondrial DNA as a Tool for Studying the Genetic Relationships of Marine Invertebrates with Planktonic Larvae: Research Fellowship in Marine Biotechnology

海洋生态学研究中的一个基本问题是识别自然种群并了解它们是如何随时间变化的。对于在发育过程中变质或在整个生命周期中改变栖息地的海洋生物来说，这一问题尤其具有挑战性。许多物种的成虫阶段是底栖的(例如，藤壶)，而它们的幼虫阶段是浮游的，可能会分散到很远的地方。近海无脊椎动物成虫种群生态学的许多方面已经得到了深入的研究，但幼虫扩散对种群遗传结构的影响尚不清楚，而且可能是广泛的。这种团契研究的目标是了解扩散和选择在多大程度上结合起来影响种群之间的差异。遗传差异可能通过自然选择、遗传漂变、非随机交配和突变而产生。种群间的基因流动减少了分化：卵子、精子、幼虫、包囊或成虫等繁殖体的传播。这两种力量通常处于不断变化的状态，我们在某个时间点上看到的遗传模式取决于这两种力量的相对强度。韦斯特博士将比较浮游藤壶幼虫和新定居幼虫的线粒体DNA序列，这些幼虫是在成虫附近收集的。这些群体之间的差异以及队列内可能随着时间的推移而发生的变化，将为这些群体的遗传结构的形成和维持提供一个新的视角。线粒体DNA分析可以揭示幼虫作为亲缘关系密切的个体的云层移动的程度。随着时间的推移，对这些模式的持续采样可以为种群自然经历的基因波动量提供线索。这些研究是通过使用聚合酶链式反应(PCR)的引物指导的酶DNA扩增来实现的。

A fundamental problem in the study of marine ecology is to identify natural populations and understand how they change through time. This problem is especially challenging in marine organisms that metamorphose during development or change habitats throughout their life cycle. Adult stages of many species are benthic (e.g. barnacles), while their larval stages are planktonic and may disperse over long distances. Many aspects of the ecology of adult populations of coastal invertebrates have been intensively studied, but the effects of larval dispersal on genetic structure of populations are unclear and potentially extensive. The goal of this fellowship research is to gain knowledge of the degree to which dispersal and selection combine to affect variation between populations. Genetic differences may arise via natural selection, genetic drift, non-random mating, and mutation. Differentiation is reduced by gene-flow between populations: dispersal of propagules such as eggs, sperm, larvae, cysts, or adults. These two forces are usually in a state of flux and the genetic patterns we see at one point in time depend on the relative strengths of these forces. Dr. West will compare individual mitochondrial DNA sequences of planktonic barnacle larvae and newly settled juveniles collected adjacent to adult sites. Differences between these groups and possibly changes within cohorts through time will yield a new perspective on formation and maintenance of the genetic structure of these populations. Mitochondrial DNA analysis can reveal the degree to which larvae travel as clouds of closely related individuals. Continued sampling of these patterns through time gives clues to the amount of genetic fluctuation that a population may naturally experience. The studies are made possible by means of primer-directed enzymatic DNA amplification using the polymerase chain reaction (PCR).