Inferring the evolutionary histories of the Adh and Adh-dup loci in Drosophila melanogaster from patterns of polymorphism and divergence.
Inferring the evolutionary histories of the Adh and Adh-dup loci in Drosophila melanogaster from patterns of polymorphism and divergence.
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作者：
M. Kreitman;R. Hudson
11个果蝇品系的DNA序列在三个连续区域，Adh和Adh-dup基因座和Adh的非编码5'侧翼区进行比较。大约4750个位点中有98个在样品中分离，36个在5'侧翼区，38个在Adh中，24个在Adh-dup中。本文提出了几种方法来检验多态性的模式和水平是否与中性分子进化一致。内和种间多态性的分析表明，该地区正在演变的非中性和复杂的方式。图形分析的数据提供了一个假设的平衡多态性或附近的位置1490，网站之间的Adhf和Adhs的氨基酸置换差异的支持。Adh-dup位点的多态性比Adh少，其所有24种多态性都以低频率发生-这表明Adh-dup区域最近发生了选择性替换。Adhs等位基因形成两个不同的进化谱系，在Adh和Adh-dup基因座中总共有19个位点彼此不同。多态性处于完全连锁不平衡。重组实验未能找到两个等位基因类别之间的重组抑制的证据。两个假设，提出了两个不同的谱系在自然种群中的广泛分布。自然选择似乎发挥了重要作用，在管理的整体模式的核苷酸变异的两个基因区域。
The DNA sequences of 11 Drosophila melanogaster lines are compared across three contiguous regions, the Adh and Adh-dup loci and a noncoding 5' flanking region of Adh. Ninety-eight of approximately 4750 sites are segregating in the sample, 36 in the 5' flanking region, 38 in Adh and 24 in Adh-dup. Several methods are presented to test whether the patterns and levels of polymorphism are consistent with neutral molecular evolution. The analysis of within- and between-species polymorphism indicates that the region is evolving in a nonneutral and complex fashion. A graphical analysis of the data provides support for a hypothesized balanced polymorphism at or near position 1490, site of the amino acid replacement difference between Adhf and Adhs. The Adh-dup locus is less polymorphic than Adh and all 24 of its polymorphisms occur at low frequency--suggestive of a recent selective substitution in the Adh-dup region. Adhs alleles form two distinct evolutionary lineages that differ one from another at a total of nineteen sites in the Adh and Adh-dup loci. The polymorphisms are in complete linkage disequilibrium. A recombination experiment failed to find evidence for recombination suppression between the two allelic classes. Two hypotheses are presented to account for the widespread distribution of the two divergent lineages in natural populations. Natural selection appears to have played an important role in governing the overall patterns of nucleotide variation across the two-gene region.