Deleterious mutation accumulation in organelle genomes
Deleterious mutation accumulation in organelle genomes
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DOI：
10.1023/a:1017022522486
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发表时间：
1998-01-01
期刊：
影响因子：
1.5
通讯作者：
Blanchard, JL
中科院分区：
文献类型：
--
作者：
Lynch, M;Blanchard, JL
在非重组基因组中轻度有害突变的积累是专性无性种群灭绝的主要风险，这在理论上已经很好地建立起来。有性群体还可能导致很少或没有重组的基因组区域发生突变恶化，即，着丝粒附近的常染色体区域、Y染色体和细胞器基因组。我们的研究结果表明，对于广泛的基因（转移RNA，核糖体RNA和蛋白质）在一个不同的物种（动物，植物和真菌）的集合，几乎普遍增加的固定概率中产生的线粒体和叶绿体基因组相对于那些在重组核基因组中产生的轻度有害突变。细胞器基因组中选择筛的宽度增加似乎不是放松选择的结果，而是可以解释为单亲遗传导致有效群体大小减少而导致的选择效率下降。由于细胞器基因组的突变率非常低（大约每年每个基因组10（-4）个），因此这些基因组中突变积累导致的适合度降低是一个非常长期的过程，在不到一百万年的时间尺度上不太可能危及许多物种，但在1000万到1亿年的时间尺度上，可能在系统发育谱系排序中发挥一定作用。
It is well established on theoretical grounds that the accumulation of mildly deleterious mutations in nonrecombining genomes is a major extinction risk in obligately asexual populations. Sexual populations can also incur mutational deterioration in genomic regions that experience little or no recombination, i.e., autosomal regions near centromeres, Y chromosomes, and organelle genomes. Our results suggest, for a wide array of genes (transfer RNAs, ribosomal RNAs, and proteins) in a diverse collection of species (animals, plants, and fungi), an almost universal increase in the fixation probabilities of mildly deleterious mutations arising in mitochondrial and chloroplast genomes relative to those arising in the recombining nuclear genome. This enhanced width of the selective sieve in organelle genomes does not appear to be a consequence of relaxed selection, but can be explained by the decline in the efficiency of selection that results from the reduction of effective population size induced by uniparental inheritance. Because of the very low mutation rates of organelle genomes (on the order of 10(-4) per genome per year), the reduction in fitness resulting from mutation accumulation in such genomes is a very long-term process, not likely to imperil many species on time scales of less than a million years, but perhaps playing some role in phylogenetic lineage sorting on time scales of 10 to 100 million years.