Reproductive fitness of Callosobruchus maculatus mtDNA haplotypes

Mitochondrial DNA (mtDNA) consists of few but vital maternally inherited genes that interact closely with nuclear genes to produce cellular energy. How important mtDNA polymorphism is for adaptation is still unclear. The assumption in population genetic studies is often that segregating mtDNA variation is selectively neutral. This contrasts with empirical observations of mtDNA haplotypes affecting fitness related traits and thermal sensitivity, and latitudinal clines in mtDNA haplotype frequencies. Here we experimentally test whether ambient temperature affects selection on mtDNA variation, and whether such thermal effects are influenced by intergenomic epistasis due to interactions between mitochondrial and nuclear genes, using replicated experimental evolution in Callosobruchus maculatus seed beetle populations seeded with a mixture of different mtDNA haplotypes. We also test for sex-specific consequences of mtDNA evolution on reproductive success, given that mtDNA mutations can have ...

线粒体DNA（mtDNA）仅包含少数但至关重要的母系遗传基因，这些基因与核基因紧密协作以产生细胞能量。目前学界尚不清楚线粒体DNA多态性对生物适应性的具体重要程度。种群遗传学研究中通常默认，分离得到的线粒体DNA变异具有选择中性。但这与多项实证观测结果相悖：观测发现线粒体DNA单倍型（haplotype）会影响与适合度相关的性状及热敏感性，且线粒体DNA单倍型频率存在纬度梯度分布现象。本研究以由不同线粒体DNA单倍型混合构建的豆象（Callosobruchus maculatus）种群为材料，通过重复实验进化实验，开展两项核心验证：其一，环境温度是否会对线粒体DNA变异的选择作用产生影响；其二，此类温度效应是否会因线粒体与核基因的相互作用，受到基因组间上位性（epistasis）的调控。此外，鉴于线粒体DNA突变可能会……，本研究还将检验线粒体DNA进化对繁殖成功率的性别特异性影响。