Dobler R, Rogell B, Budar F, Dowling D K
Institute of Evolution and Ecology, University of Tübingen, Tübingen, Germany.
J Evol Biol. 2014 Oct;27(10):2021-34. doi: 10.1111/jeb.12468. Epub 2014 Sep 4.
Genetic variation in cytoplasmic genomes (i.e. the mitochondrial genome in animals, and the combined mitochondrial and chloroplast genomes in plants) was traditionally assumed to accumulate under a neutral equilibrium model. This view has, however, come under increasing challenge from studies that have experimentally linked cytoplasmic genetic effects to the expression of life history phenotypes. Such results suggest that genetic variance located within the cytoplasm might be of evolutionary importance and potentially involved in shaping population evolutionary trajectories. As a step towards assessing this assertion, here we conduct a formal meta-analytic review to quantitatively assess the extent to which cytoplasmic genetic effects contribute to phenotypic expression across animal and plant kingdoms. We report that cytoplasmic effect sizes are generally moderate in size and associated with variation across a range of factors. Specifically, cytoplasmic effects on morphological traits are generally larger than those on life history or metabolic traits. Cytoplasmic effect sizes estimated at the between-species scale (via interspecies mix-and-matching of cytoplasmic and nuclear genomes) are larger than those at the within-species scale. Furthermore, cytoplasmic effects tied to epistatic interactions with the nuclear genome tend to be stronger than additive cytoplasmic effects, at least when restricting the data set to gonochorous animal species. Our results thus confirm that cytoplasmic genetic variation is commonly tied to phenotypic expression across plants and animals, implicate the cytoplasmic-nuclear interaction as a key unit on which natural selection acts and generally suggest that the genetic variation that lies within the cytoplasm is likely to be entwined in adaptive evolutionary processes.
传统上认为，细胞质基因组中的遗传变异（即动物中的线粒体基因组以及植物中的线粒体和叶绿体基因组的组合）是在中性平衡模型下积累的。然而，这种观点越来越受到一些研究的挑战，这些研究通过实验将细胞质遗传效应与生活史表型的表达联系起来。这些结果表明，细胞质中的遗传变异可能具有进化重要性，并可能参与塑造种群的进化轨迹。作为评估这一论断的第一步，我们在此进行了一项正式的荟萃分析综述，以定量评估细胞质遗传效应在动植物界中对表型表达的贡献程度。我们报告称，细胞质效应大小一般适中，并与一系列因素的变异相关。具体而言，细胞质对形态性状的效应通常大于对生活史或代谢性状的效应。在物种间尺度（通过细胞质和核基因组的种间混合匹配）估计的细胞质效应大小大于在物种内尺度的效应大小。此外，至少在将数据集限制为雌雄异体动物物种时，与核基因组上位相互作用相关的细胞质效应往往比加性细胞质效应更强。因此，我们的结果证实，细胞质遗传变异通常与动植物的表型表达相关，表明细胞质 - 核相互作用是自然选择作用的关键单元，并总体表明细胞质中的遗传变异可能在适应性进化过程中相互交织。
