Population genetics of the cytoplasm and the units of selection on mitochondrial DNA in Drosophila melanogaster.
Population genetics of the cytoplasm and the units of selection on mitochondrial DNA in Drosophila melanogaster.
复制标题
果蝇细胞质的群体遗传学和线粒体 DNA 选择单位。
DOI：
10.1007/s10709-011-9576-y
复制
发表时间：
2011
期刊：
影响因子：
1.5
通讯作者：
Rand,DavidM
中科院分区：
文献类型：
--
作者：
Rand,DavidM
生物变异存在于一组嵌套的等级水平上，从基因内的核苷酸到物种内的种群，再到生命树内的谱系。在进化生物学中，选择如何在这个层次上起作用是一个长期存在的问题。最近的研究表明，基因组大小在很大程度上受到不同种群大小的谱系中选择、突变和漂移的平衡的影响。在这里，我们使用群体笼子和母体传递实验来确定个体和细胞质水平上的选择的相对强度。在群体笼养的14代中，大(L)和小(S)线粒体DNA的频率没有明显的变化趋势。在所有的复制笼子中，在异质状态下观察到新的长度变异，这表明在这些实验种群中发生了自发的长度突变。携带L基因组的异质果蝇比携带S基因组的异质果蝇更常见，提示线粒体DNA从大到小是一个不对称的突变动态。异质性的母子传递表明，L线粒体DNA在果蝇体内的频率在世代之间和世代内都有所增加，尽管采样漂移的强度与种群笼子中的相同。这些结果表明，对线粒体DNA大小的选择在细胞质水平上比在有机体水平上更强。新的线粒体DNA在物种内和物种间的固定需要一个瞬时的细胞内异质阶段。细胞质和个体水平上的群体遗传力的平衡控制着mtDNA上的选择单位，并对进化推断以及mtDNA突变对健康、疾病和衰老的影响具有意义。
Biological variation exists across a nested set of hierarchical levels from nucleotides within genes to populations within species to lineages within the tree of life. How selection acts across this hierarchy is a long-standing question in evolutionary biology. Recent studies have suggested that genome size is influenced largely by the balance of selection, mutation and drift in lineages with different population sizes. Here we use population cage and maternal transmission experiments to identify the relative strength of selection at an individual and cytoplasmic level. No significant trends were observed in the frequency of large (L) and small (S) mtDNAs across 14 generations in population cages. In all replicate cages, new length variants were observed in heteroplasmic states indicating that spontaneous length mutations occurred in these experimental populations. Heteroplasmic flies carrying L genomes were more frequent than those carrying S genomes suggesting an asymmetric mutation dynamic from larger to smaller mtDNAs. Mother-offspring transmission of heteroplasmy showed that the L mtDNA increased in frequency within flies both between and within generations despite sampling drift of the same intensity as occurred in population cages. These results suggest that selection for mtDNA size is stronger at the cytoplasmic than at the organismal level. The fixation of novel mtDNAs within and between species requires a transient intracellular heteroplasmic stage. The balance of population genetic forces at the cytoplasmic and individual levels governs the units of selection on mtDNA, and has implications for evolutionary inference as well as for the effects of mtDNA mutations on fitness, disease and aging.