DISSERTATION RESEARCH: Is mitochondrial DNA lying about its age? Assessing diversification history in a species complex of sea cucumbers (Echinodermata: Holothuroidea)

论文研究：线粒体 DNA 是否谎报了其年龄？

• 批准号: 1110653
• 负责人: Gustav Paulay
• 金额: $ 1.5万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1110653&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; mitochondrial; DNA; lying

Given that species diverge mostly in geographical isolation, the dynamics of local diversity is governed by the time it takes for these species to co-occur (secondary sympatry). Based on mitochondrial DNA and morphological evidence, some echinoderms seem able to achieve secondary sympatry an order of magnitude faster than other groups of marine invertebrates. The proposed research seeks to investigate whether these patterns could alternatively be caused by introgressive hybridization masking an earlier divergence, or reflect high levels of intraspecific polymorphism obscuring similar rates of secondary sympatry. To tease apart these hypotheses, the parameters of the isolation-with-migration (IM) model will be estimated from a multilocus dataset in a complex of sea cucumbers comprised of four putative, recently diverged, species. Furthermore, computer simulations will be used to determine whether the history of some loci deviates from this model, suggesting introgressive hybridization.Results will contribute to our understanding of species limits in challenging groups, and diversification in the richest marine biogeographic region. They will also generate hypotheses on the mechanisms involved in the generation of this diversity. In particular, the estimation of gene flow and population sizes will lead to predictions on the role of these demographic parameters in speciation. Furthermore, these estimates will help improve stock delineation and estimation of sea cucumbers, a major marine resource in tropical coastal communities.

鉴于物种大多在地理上与世隔绝，当地多样性的动态取决于这些物种共存(次生共生)所需的时间。根据线粒体DNA和形态证据，一些棘皮动物似乎能够比其他海洋无脊椎动物群体更快地实现次生共生。这项拟议的研究试图调查这些模式是否可能是由导入杂交掩盖了早期的分歧造成的，或者反映了种内高水平的多态掩盖了相似的次生共生率。为了梳理这些假设，隔离-迁徙(IM)模型的参数将从一个由四个假定的、最近分离的物种组成的海参复合体的多位点数据集中估计。此外，计算机模拟将被用来确定一些基因座的历史是否偏离这一模型，建议进行渐进式杂交。结果将有助于我们理解具有挑战性的群体中的物种限制，以及最丰富的海洋生物地理区域的多样性。它们还将产生关于这种多样性产生机制的假说。特别是，对基因流和种群规模的估计将导致对这些人口统计参数在物种形成中的作用的预测。此外，这些估计数将有助于改进对海参的种群描述和估计，海参是热带沿海社区的一种主要海洋资源。