Presgraves Daven C
Department of Biology II, Ludwig-Maximilians-Universität BioCenter, Grosshaderner Str. 2, 82152 Planegg-Martinsried, Germany.
Curr Biol. 2005 Sep 20;15(18):1651-6. doi: 10.1016/j.cub.2005.07.065.
Evolutionary theory predicts that the rate and level of adaptation will be enhanced in sexual relative to asexual genomes because sexual recombination facilitates the elimination of deleterious mutations and the fixation of beneficial ones by natural selection. To date, the most compelling evidence for this prediction comes from experimental evolution studies and from loci completely lacking recombination, such as those on Y chromosomes, which often show reduced adaptation and even degeneration. Here, by analyzing replacement and silent DNA polymorphism and divergence at 98 loci, I show that recombination increases the efficacy of protein adaptation throughout the genome of the fruit fly Drosophila melanogaster. Genes residing in genomic regions with reduced recombination rates suffer a greater load of segregating, mildly deleterious mutations and fix fewer beneficial mutations than genes residing in regions with higher recombination rates. These findings suggest that the capacity to respond to natural selection varies with recombination rate across the genome, consistent with theory on the evolutionary advantages of sex and recombination.
进化理论预测，相对于无性生殖的基因组，有性生殖基因组的适应速率和适应水平将会提高，因为有性重组有助于通过自然选择消除有害突变并固定有益突变。迄今为止，这一预测最有力的证据来自实验进化研究以及完全缺乏重组的基因座，比如Y染色体上的基因座，这些基因座常常显示出适应能力降低甚至退化。在此，通过分析98个基因座上的替换和沉默DNA多态性及分化情况，我发现重组提高了果蝇黑腹果蝇整个基因组中蛋白质适应的效率。与位于重组率较高区域的基因相比，位于重组率较低基因组区域的基因承受着更大的分离负担、温和有害突变，并且固定的有益突变更少。这些发现表明，对自然选择作出反应的能力会随着基因组中重组率的变化而变化，这与关于有性生殖和重组的进化优势的理论一致。
