Selfish Mitochondrial DNA Proliferates and Diversifies in Small, but not Large, Experimental Populations of Caenorhabditis briggsae.
Selfish Mitochondrial DNA Proliferates and Diversifies in Small, but not Large, Experimental Populations of Caenorhabditis briggsae.
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DOI：
10.1093/gbe/evv116
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发表时间：
2015-06-24
影响因子：
3.3
通讯作者：
Denver DR
中科院分区：
文献类型：
--
作者：
Phillips WS;Coleman-Hulbert AL;Weiss ES;Howe DK;Ping S;Wernick RI;Estes S;Denver DR
跨生物组织水平的进化相互作用有助于各种基本过程，包括基因组进化、生殖模式转变、物种多样化和灭绝。进化理论预测，当宿主的有效种群规模（Ne）很小时，所谓的“自私”遗传因子将增殖，但对这一预测的直接测试仍然很少。我们分析了含有缺失的线粒体DNA（ΔmtDNA）分子的进化动力学，以前被描述为自私的元素，在6种不同的自然线虫中，允许在一系列种群规模（N = 1，10，100和1，000）中进行实验进化，最多50代。在每个五代时间点分析线粒体DNA（mtDNA）的重复谱系。在实验群体中观察到10种不同的ΔmtDNA分子类型。与进化理论的预测一致，实验室品系在小种群规模中进化（例如，与较大种群中进化的Δ线粒体DNA相比，线虫N = 1）更容易积累高水平的预先存在的Δ线粒体DNA。新的ΔmtDNA元件被观察到频率增加，并持续跨时间点，但几乎只在小的人口规模。在某些情况下，当种群规模较大（线虫N = 1，000）时，ΔmtDNA水平在世代间下降。不同的自然菌株C. Briggsae对ΔmtDNA积累的敏感性各不相同，部分原因是在某些菌株中预先存在的防止缺失形成的补偿性mtDNA等位基因。这一分析直接表明ΔmtDNA元件的进化轨迹依赖于其宿主的群体遗传环境和分子遗传特征。
Evolutionary interactions across levels of biological organization contribute to a variety of fundamental processes including genome evolution, reproductive mode transitions, species diversification, and extinction. Evolutionary theory predicts that so-called “selfish” genetic elements will proliferate when the host effective population size (Ne) is small, but direct tests of this prediction remain few. We analyzed the evolutionary dynamics of deletion-containing mitochondrial DNA (ΔmtDNA) molecules, previously characterized as selfish elements, in six different natural strains of the nematode Caenorhabditis briggsae allowed to undergo experimental evolution in a range of population sizes (N = 1, 10, 100, and 1,000) for a maximum of 50 generations. Mitochondrial DNA (mtDNA) was analyzed for replicate lineages at each five-generation time point. Ten different ΔmtDNA molecule types were observed and characterized across generations in the experimental populations. Consistent with predictions from evolutionary theory, lab lines evolved in small-population sizes (e.g., nematode N = 1) were more susceptible to accumulation of high levels of preexisting ΔmtDNA compared with those evolved in larger populations. New ΔmtDNA elements were observed to increase in frequency and persist across time points, but almost exclusively at small population sizes. In some cases, ΔmtDNA levels decreased across generations when population size was large (nematode N = 1,000). Different natural strains of C. briggsae varied in their susceptibilities to ΔmtDNA accumulation, owing in part to preexisting compensatory mtDNA alleles in some strains that prevent deletion formation. This analysis directly demonstrates that the evolutionary trajectories of ΔmtDNA elements depend upon the population-genetic environments and molecular-genetic features of their hosts.