Evolutionary Consequences of Restricted Gene Flow in a Marine Copepod

海洋桡足类基因流受限的进化后果

• 批准号: 9409066
• 负责人: Ronald Burton
• 金额: $ 29.4万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-12-15 至 1999-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9409066&HistoricalAwards=false
• 关键词: Evolutionary; Consequences; Restricted; Gene; Flow

Burton 9409066 The processes by which populations of organisms differentiate genetically and physiologically, achieve reproduction isolation,and ultimately undergo speciation are poorly understood. Using the intertidal copepod Tigriopus californicus as model system, levels of genetic differentialtion and reproductive isolation will be determined for populations in two geographic locations of specific interest: (1) the region around Point Conception (west of Santa Barbara, California) and (2) the north central coast of Baja California. The former region spans a geographic discontinuity in the historic distribution of the species. The latter region extends across the central coast of Baja, where a reproductively isolated population of Tigriopus has recently been found. Analysis of a series of populations in this region will span what appears to be a case of incipient speciation. Comparisons will be made of levels of allozyme differentiation and DNA sequence divergence across the two study regions- one that is marked by reproductive isolation and one that is not so marked - to gain insight into the consequence of restricted gene flow in Tigriopus. In addition to these descriptive studies, analysis of the function of cytochrome c oxidase (CO, EC 1.9.3.1) activity in interpopulation hybrids will be initiated. Because CO is composed of multiple nuclear and mitochondrially- encoded subunits, CO activity may be particularly sensitive to intergenomic functional integration (coadaptation). Analysis of CO enzymatic activity in control and back-crossed lines will be used to test whether normal patterns of inheritance of CO activity are perturbed by cytonuclear interaction in interpopulation in crosses. Several basic and applied issues concerning analysis of population structure will be addressed by the data. (1) What are the relationships among mtDNA sequence variation, nucDNA sequence variation, allozyme variation and reproductive compatibility highly subdivided populations? (2) Wh at are the relative sensitivities of DNA sequencing and allozyme studies for detecting population structure? (3) Are mtDNA haplotypes within a species functionally equivalent as is commonly assumed in phylogeographic studies, or have specific cytonuclear coadapted complexes evolved within geographically separated populations? (4) To what extent are biogeographic boundaries reflected in the genetic structure of species that span the boundaries? Issues (1-3) are important in developing methodologies for analysis of biodiversity in marine and terrestrial systems, while (4) is particularly relevant to assessing the biological impact of global climatic change.

伯顿9409066 生物种群在遗传和生理上的差异，实现生殖隔离，并最终经历物种形成的过程知之甚少。 以潮间带桡足类加州虎足虫（Tigriopus californicus）为模型系统，测定了两个地理位置种群的遗传分化和生殖隔离水平：（1）Point Conception（圣巴巴拉以西，加州）周围地区和（2）下加利福尼亚中北部海岸。 前一个地区跨越了该物种历史分布的地理间断。 后一个地区延伸到整个中部海岸的巴哈，在那里的生殖隔离人口的Tigriopus最近被发现。在这个地区的一系列人口的分析将跨越什么似乎是一个早期物种形成的情况。 比较将在两个研究区域的等位酶分化和DNA序列分歧的水平-一个是由生殖隔离，一个是不那么明显-深入了解的后果，限制基因流在Tigriopus。 除了这些描述性研究外，还将开始分析细胞色素c氧化酶（CO，EC 1.9.3.1）活性在种群间杂交中的功能。 因为一氧化碳是由多个核和神经编码的 由于C1亚基的存在，CO活性可能对基因组间的功能整合（共适应）特别敏感。 对照和回交品系中的CO酶活性分析将用于测试CO活性的正常遗传模式是否受到杂交中群体间细胞核相互作用的干扰。 有关人口结构分析的几个基本和应用问题将由数据来解决。 (1)线粒体DNA序列变异、核DNA序列变异、等位酶变异与生殖亲和性高度亚群之间的关系是什么？ (2)DNA测序和等位酶研究在检测群体结构方面的相对灵敏度是多少？ (3)mtDNA单倍型在一个物种内是否如地理学研究中通常假设的那样在功能上是等同的，或者在地理上分离的种群内是否进化出了特定的细胞核共适应复合体？ (4)地理边界在多大程度上反映在跨越边界的物种的遗传结构中？ 问题（1-3）对于制定海洋和陆地系统生物多样性分析方法很重要，而问题（4）对于评估全球气候变化的生物影响特别重要。