Speciation and Gene Flow in the Open Ocean: the Phylogeography of an Oceanic Copepod Family

该项目将开发一个研究海洋浮游动物种群物种形成的模型系统，以研究在开阔海洋物种形成过程中重要的地理和生态因素。 哲水蚤桡足类真哲水蚤科是海洋分布，组成物种很可能已经完全在开放的海洋中进化。 该科现存的23个物种将作为我们的模型系统。 研究将包括两个部分。首先，将开发基于一个线粒体（16S rDNA）和一个核（延伸因子-1-a）基因位点的物种水平的分子遗传学，包括该家族内的所有已知物种。 姐妹种对将根据亲缘关系确定。 三个中心的假设正在测试有关的比较地理分布，形态特征和遗传多样性，这些姐妹种对。结果将阐明模式的范围重叠，后物种范围的演变，生殖形态特征的分歧，生态特征的分歧，以及历史种群规模的差异。 这样的结果将提供深入了解那些在物种形成过程中发挥作用的因素。第二，种内，研究的一部分，将检查在环球Eucalanus hyalinus s.l.遗传谱系的地理分布。和鼻哲水蚤Rhincalanus nasutus s.l. 这一部分将确定在全球范围内造成同种种群之间基因流动界限的海洋学特征。 将基于线粒体基因座细胞色素氧化酶I（COI）生成种内单倍型网络。第二部分研究的目标是了解种群如何经历初始分化过程，这是物种形成模型的关键步骤。初步结果表明，所提出的工作的巨大潜在价值。 在该科中至少发现了三个以前神秘的物种，目前对现有物种的地理分布的理解已经被修改。 线粒体DNA分子遗传学的DNA测序工作已经完成了一半，这项工作所需的大部分标本已经收集完毕。这项研究所产生的序列将存入基因库，从而广泛传播给所有感兴趣的各方。 本研究为博士研究。 除了回答提出的具体问题外，这项建议将有助于培养具有系统学和现代分子技术能力的新一代海洋学家。

This project will develop a model system for the study of speciation in marine holozooplankton populations, to examine the biogeographic and ecological factors important during speciation in the open ocean. The calanoid copepod family Eucalanidae is oceanic in distribution, and component species are likely to have evolved entirely in the open ocean. The 23 extant species in this family will serve as our model system. The research will consist of two parts. First, a species level molecular phylogeny based on one mitochondrial (16s rDNA) and one nuclear (Elongation Factor-1-a) gene locus will be developed, including all known species within the family. Sister species pairs will be identified based on the phylogeny. Three central hypotheses are being tested regarding the comparative biogeographic distributions, morphological characteristics, and genetic diversity of these sister species pairs. Results will elucidate patterns in the extent of biogeographic range overlap, post-speciational range evolution, divergence in reproductive morphological characteristics, divergence in ecological characteristics, and differences in historical population sizes. Such results will provide insight into those factors that play a role in the speciation process. The second, intraspecific, part of the study will examine geographic distributions of genetic lineages in circumglobal Eucalanus hyalinus s.l. and Rhincalanus nasutus s.l. This component will identify oceanographic features that create boundaries to gene flow between conspecific populations on a global scale. Intraspecific haplotype networks will be generated based on the mitochondrial gene locus Cytochrome Oxidase I (COI). The goal of this second portion of the research is to understand how populations undergo the initial differentiation process, a step critical to speciation models. Initial results demonstrate the tremendous potential value of the proposed work. At least three previously cryptic species have been uncovered within the family, and current understanding of the biogeographic distributions of existing species has been modified. Half of the DNA sequencing for the mtDNA molecular phylogeny has been completed, and most of the specimens required for this work have already been collected. The sequences resulting from this research will be deposited in GenBank, and thus disseminated broadly to all interested parties. The proposed research is the doctoral study. In addition to answering the specific questions posed, this proposal will contribute to the training of a new generation of oceanographers with abilities in systematics and modern molecular techniques.