Keith T P, Brooks L D, Lewontin R C, Martinez-Cruzado J C, Rigby D L
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138.
Mol Biol Evol. 1985 May;2(3):206-16. doi: 10.1093/oxfordjournals.molbev.a040348.
In a previous study, Keith (1983) showed by sequential gel electrophoresis of the esterase-5 protein in Drosophila pseudoobscura that a highly polymorphic locus with many alleles can have very similar frequency distributions in populations separated by 500 km. The present work studies another highly polymorphic locus, xanthine dehydrogenase, in the same California population samples, using the same technique to distinguish allelic classes. Twelve electromorphs were found in one population and 15 in the other. Both populations shared a single very frequent (approximately 60%) allele, as well as five other alleles in low but similar frequencies. In addition, each population had an array of unique alleles present only once in one population sample but absent in the other. A statistical test against the stationary distribution for neutral alleles shows that, if the populations are at equilibrium, then purifying selection is operating on xanthine dehydrogenase. The extremely close similarity in frequency distributions of the alleles between populations for both the xanthine dehydrogenase and esterase-5 loci, despite differences in allele frequency distribution between loci, strongly emphasizes the importance of migration in influencing genic diversity in these populations.
在之前的一项研究中，基思（1983年）通过对拟暗果蝇酯酶-5蛋白进行连续凝胶电泳表明，一个具有许多等位基因的高度多态性位点在相距500公里的种群中可能具有非常相似的频率分布。本研究使用相同的技术来区分等位基因类别，对加利福尼亚州相同的种群样本中的另一个高度多态性位点——黄嘌呤脱氢酶进行了研究。在一个种群中发现了12种电泳形态，在另一个种群中发现了15种。两个种群都有一个非常常见（约60%）的等位基因，以及其他五个频率较低但相似的等位基因。此外，每个种群都有一系列独特的等位基因，这些等位基因在一个种群样本中只出现一次，而在另一个种群中不存在。针对中性等位基因的固定分布进行的统计检验表明，如果种群处于平衡状态，那么对黄嘌呤脱氢酶正在进行纯化选择。尽管两个位点的等位基因频率分布存在差异，但黄嘌呤脱氢酶和酯酶-5位点在种群之间的等位基因频率分布极其相似，这强烈强调了迁移在影响这些种群基因多样性方面的重要性。
