Ballard J W
The Field Museum, 1400 S. Lake Shore Drive, Chicago, IL 60605-2496, USA.
J Mol Evol. 2000 Jul;51(1):64-75. doi: 10.1007/s002390010067.
The current study compares the nucleotide variation among 22 complete mitochondrial genomes of the three distinct Drosophila simulans haplotypes with intron 1 of the alcohol dehydrogenase-related locus. This is the first study to investigate the sequence variation of multiple complete mitochondrial genomes within distinct mitochondrial haplotypes of a single species. Patterns of variation suggest distinct forces are influencing the evolution of mitochondrial DNA (mtDNA) and autosomal DNA in D. simulans. First, there is little variation within each mtDNA haplotype but strong differentiation among them. In contrast, there is no support for differentiation of the mitochondrial haplotypes at the autosomal locus. Second, there is a significant deficiency of mitochondrial variation in each haplotype relative to the autosomal locus. Third, the ratio of nonsynonymous to synonymous substitutions is not equal in all branches of the well-resolved phylogeny. There is an excess of nonsynonymous substitutions relative to synonymous substitutions within each D. simulans haplotype. This result is similar to that previously observed within the mtDNA of distinct species. A single evolutionary force may be causally linked to the observed patterns of mtDNA variation-a rickettsia-like microorganism, Wolbachia pipientis, which is known to directly influence mitochondrial evolution but have a less direct influence on autosomal loci.
本研究比较了三种不同的拟暗果蝇单倍型的22个完整线粒体基因组与乙醇脱氢酶相关基因座内含子1之间的核苷酸变异。这是首次在单一物种的不同线粒体单倍型内研究多个完整线粒体基因组的序列变异。变异模式表明，不同的力量正在影响拟暗果蝇中线粒体DNA（mtDNA）和常染色体DNA的进化。首先，每个mtDNA单倍型内变异很少，但它们之间存在强烈分化。相比之下，在常染色体基因座上没有证据支持线粒体单倍型的分化。其次，相对于常染色体基因座，每个单倍型中的线粒体变异明显不足。第三，在解析良好的系统发育树的所有分支中，非同义替换与同义替换的比例并不相等。在每个拟暗果蝇单倍型中，非同义替换相对于同义替换过多。这一结果与先前在不同物种的mtDNA中观察到的结果相似一种单一的进化力量可能与观察到的mtDNA变异模式有因果关系——一种立克次氏体样微生物，嗜菌异小杆线虫，已知它直接影响线粒体进化，但对常染色体基因座的影响较小。
