Gene Flow and Divergence Across the Equatorial Tropical Marine Barrier: Past, Present and Future

跨越赤道热带海洋屏障的基因流和分歧：过去、现在和未来

• 批准号: 0961996
• 负责人: Peter Marko
• 金额: $ 56.82万
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961996&HistoricalAwards=false
• 关键词: Gene; Flow; Divergence; Across; Equatorial

The marine communities of the northern and southern hemispheres are kept distinct by warm water and strong currents near the equator. Nevertheless, many taxa have established "antitropical" distributions, occurring in temperate zones on either side of the tropics but not within the warmest tropical regions. Although paleontological studies and molecular phylogenies provide information about the timing and direction of trans-tropical colonization, the existence of single species with antitropical distributions provides an opportunity to begin to investigate several fundamental questions about the recent history of and future prospects for biological connectivity between the northern and southern hemispheres. This project focuses on characterizing connectivity across the tropics in the antitropical gooseneck barnacle Pollicipes elegans. This eastern Pacific species is found in both hemispheres but is absent from the warmest waters immediately to the north of the equator. Previously-collected data show that mtDNA haplotype lineages are shared between northern and southern hemisphere populations, and that the separation between north and south has been relatively recent, within the last 160,000 years. This research has two main goals. First, the investigators will use multi-locus sequence data and microsatellite loci to estimate the time of separation of northern and southern populations and how much gene flow has occurred since that split, both over evolutionary timescales and across recent generations. The second goal is to characterize larval thermal tolerance and performance as a means to test the hypothesis that temperature is a barrier to larval dispersal across the warmest tropical regions in P. elegans. Although several other hypotheses can potentially explain what keeps P. elegans out of the tropics, such as the isolating effects of the equatorial boundary currents or post-settlement processes, assessing the temperature sensitivity of the dispersive larval stage will provide the first important physiological test of how temperature limits connectivity. Understanding the history of gene flow and the temperature tolerance of dispersive larvae will provide insight into the impacts of recent and projected increases in tropical sea surface temperatures on recent and future patterns of connectivity between the hemispheres.This project will provide financial support and training in fieldwork, population genetics, and larval ecology for two graduate students and two postdoctoral researchers. Undergraduate students will be involved with aspects of the research through a hands-on lab class taught in Molecular Population Biology and recruitment from courses taught at Clemson. The investigators will also continue to engage a local school district (LaFrance, South Carolina) via classroom visits by scientists (PI, graduate students, and postdocs). The investigators publish actively in leading scientific journals and written invited contributions for the fields of biogeography and life history evolution. Research in the their labs is disseminated via web pages and previous work has reached the public through a wide variety of media outlets.

北半球和南半球的海洋群落被赤道附近的温水和强潮流保持不同。然而，许多分类单元已经建立了“抗性”分布，发生在热带两侧的温带区域，但不在最温暖的热带地区。尽管古生物学研究和分子系统发育提供了有关跨热带定殖的时间和方向的信息，但具有抗性分布的单个物种的存在提供了一个机会，可以开始研究有关北半球和南半球之间生物学连通性的最新历史的几个基本问​​题。该项目的重点是表征抗杀菌剂的热带地区的连通性。在两个半球中都发现了这种东部太平洋物种，但在赤道北部的最温暖的水域都没有。先前收集的数据表明，北半球和南半球种群之间共享mtDNA单倍型谱系，并且在过去的160，000年内，北部和南方之间的分离相对较新。这项研究有两个主要目标。首先，研究人员将使用多层次的序列数据和微卫星基因座来估计北部和南部人群分离的时间，以及自分裂以来的基因流量发生了多少，无论是在进化时代范围内以及最近几代人。第二个目标是表征幼虫的热耐受性和性能，以此来检验假设，即温度是秀丽隐杆线虫最温暖的热带地区幼体分散的障碍。尽管其他几个假设可以潜在地解释是什么使秀丽隐杆线远离热带地区，例如赤道边界电流的隔离效应或分配后过程，评估分散幼虫阶段的温度敏感性将提供第一个重要的生理测试，以实现如何限制温度连接。了解基因流量的历史以及分散幼虫的温度耐受性将提供有关热带海面温度最近和预计增加的影响对半球连通性最近和未来连通模式的影响的洞察力。该项目将为两位研究生遗传学，人口遗传学以及两位研究生的学生和两位研究生研究人员和两位研究生研究人员和两位研究生的培训提供财务支持和培训。本科生将通过在克莱姆森（Clemson）教授的课程中以分子种群生物学和招募招聘的动手实验室课程参与研究的各个方面。调查人员还将通过科学家（PI，研究生和博士后）的课堂访问来继续与当地学区（南卡罗来纳州的Lafrance）互动。研究人员积极发表了领先的科学期刊，并为生物地理学和生活历史进化领域的书面贡献提供了贡献。他们的实验室的研究通过网页进行了传播，以前的工作已通过各种媒体吸引了公众。