Dissertation Research: Patterns of Genetic Variation in Natural Populations: Chromosomal, Single Gene, and Polygenic

了解分布在离散种群中的生物的种群遗传结构对于理解这些种群的后续进化是至关重要的。大多数研究使用等位酶来检查种群内部和种群之间的遗传变异模式，而忽略了染色体和形态变异等来源。这些额外的变异源预计将与等位酶变异形成对比。在染色体变异的传播和/或固定过程中，漂移等随机过程应该是重要的，因为染色体排列的杂合个体经常被观察到生育力降低。然而，作用于形态特征的选择可以抵消这种随机过程。等位酶，被认为是中性的遗传标记，将受到随机过程的影响，在染色体变异的固定中可能是重要的。综合考虑所有三种变异来源，染色体变异与同工酶的关系应该比与形态变异的关系更密切。coPI将研究克拉克氏菌（Clarkia dudleyana）的单基因（等位酶和离散形态特征）和多基因（定量遗传）变异在种群内和种群间的染色体变异模式。克拉克氏菌是一种已知在种群间含有染色体多态性的物种。coPI将检查染色体关系，估计等位酶和形态特征的基因频率，并检查8个自然种群的多基因变异模式。coPI还将研究选择，以确定当前的选择制度是否与形态变异模式的差异相一致，而不是与等位酶和染色体变异相一致。这项研究的总体意义在于，它将提高我们对自然植物种群的生存和传播的理解。

Understanding the population genetic structure of organisms distributed in discrete populations is essential to understanding the subsequent evolution of such populations. Most studies examine the pattern of genetic variation within and among populations using allozymes, neglecting sources such as chromosomal and morphological variation. These additional sources of variation are expected to contrast with allozyme variation. Random processes such as drift should be important in the spread and/or fixation of chromosomal variants since individuals heterozygous for chromosome arrangements are often observed to have reduced fertility. Selection acting on morphological traits, however, can counteract such random processes. Allozymes, assumed to be neutral genetic markers, will be affected by random processes potentially important in fixation of chromosomal variants. Considering all three sources of variation together, chromosomal variation should coincide more closely with allozyme than with morphological variation. The coPI will examine the within and among population patterns of chromosomal variation in relation to both single gene (allozymes and discrete morphological traits) and polygenic (quantitative genetic) variation in Clarkia dudleyana, a species known to contain chromosomal polymorphism between populations. The coPI will examine the chromosomal relationship, estimate gene frequencies of both allozymes and morphological traits, and examine the pattern of polygenic variation for eight natural populations. The coPI will also study selection to determine whether current selection regimes are consistent with differences in the pattern of morphological variation as compared to allozyme and chromosomal variation. The general significance of the study is that it will improve our understanding of the survival and spread of natural plant populations.