Dissertation Research: The Effect of Breeding System on the Level and Pattern of Molecular Variation in Plant Populations

9532071查尔斯沃斯这项研究将检验最近的理论，即高度自交的物种应该在中性变异中恶化。从理论上讲，植物种群的遗传变异模式和数量很大程度上受交配系统的影响，而交配系统又受自交受精率的强烈影响。核苷酸序列变异将在一组自交受精率存在已知差异的植物中进行量化(莱文沃西亚；十字花科)。由此产生的数据将允许比较具有不同繁育系统的分类群在核苷酸水平上的中性和与适应性相关的变异水平。了解近亲交配对中性和适合度相关基因座遗传变异的影响，以及种群间各种遗传多样性差异的原因，对植物遗传学的各个方面都具有重要意义。对自然种群遗传变异的研究结果也将对植物遗传保护有价值。保护生物学家认为，近亲繁殖的类群非常容易受到环境退化的影响，因为它们在影响适合度的特征中遗传变异性的储存量很低。这项受资助的研究通过量化这些高度近亲繁殖的种群与适应相关的遗传变异来解决这一假设的有效性。核苷酸序列数据可以进一步用于推断所研究群体的系统发育。这反过来将为理解该属繁育系统性状和生活史特征的进化史提供一个有价值的框架。

9532071 CHARLESWORTH This research will test recent theories that highly selfing species should be depauperate in neutral variation. Theoretically, the pattern and amount of genetic variation in plant populations are greatly influenced by the mating system which, in turn, is strongly influenced by the self-fertilization rate. Nucleotide sequence variation will be quantified in a group of plants with known differences in self-fertilization rates (Leavenworthia ; Brassicaceae). The resulting data will allow the comparison of levels of neutral and fitness-related variation at the nucleotide level among taxa with diverse breeding systems. Understanding the influence of inbreeding on genetic variability at neutral and fitness related loci, and the causes of differences in each kind of genetic diversity among populations, is important in relation to all aspects of plant genetics. Findings on genetic variation from natural populations will also be of value for plant genetic conservation. Conservation biologists assume that inbreeding taxa are highly susceptible to environmental degradation, because of their low reservoir of genetic variability in traits affecting fitness. The funded research addresses the validity of this assumption by quantifying fitness-related genetic variation for such highly inbred populations. The nucleotide sequence data can be further utilized for inferring the phylogeny of the group studied. This will, in turn, ppovide a valuable framework for understanding the evolutionary history of breeding system traits and life history characters in the genus.