Immonen Elina, Berger David, Sayadi Ahmed, Liljestrand-Rönn Johanna, Arnqvist Göran
Department of Ecology and Evolution/Evolutionary Biology Uppsala University Uppsala Sweden.
Department of Ecology and Evolution/Animal Ecology Uppsala University Uppsala Sweden.
Ecol Evol. 2020 Sep 17;10(20):11387-11398. doi: 10.1002/ece3.6775. eCollection 2020 Oct.
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 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 sexually antagonistic fitness effects. Our results demonstrate natural selection on mtDNA haplotypes, with some support for thermal environment influencing mtDNA evolution through mitonuclear epistasis. The changes in male and female reproductive fitness were both aligned with changes in mtDNA haplotype frequencies, suggesting that natural selection on mtDNA is sexually concordant in stressful thermal environments. We discuss the implications of our findings for the evolution of mtDNA.
线粒体DNA（mtDNA）由少数但至关重要的母系遗传基因组成，这些基因与核基因密切相互作用以产生细胞能量。mtDNA多态性对适应性有多重要仍不清楚。群体遗传学研究中的假设通常是，分离的mtDNA变异是选择性中性的。这与mtDNA单倍型影响与适应性相关性状和热敏感性以及mtDNA单倍型频率的纬度梯度的实证观察结果形成对比。在这里，我们通过在接种了不同mtDNA单倍型混合物的种子甲虫种群中进行重复实验进化，来实验性地测试环境温度是否影响对mtDNA变异的选择，以及这种热效应是否受到线粒体和核基因之间相互作用导致的基因组间上位性的影响。鉴于mtDNA突变可能具有性拮抗适应性效应，我们还测试了mtDNA进化对繁殖成功的性别特异性后果。我们的结果证明了对mtDNA单倍型的自然选择，并且有一些证据支持热环境通过线粒体-核上位性影响mtDNA进化。雄性和雌性繁殖适应性的变化都与mtDNA单倍型频率的变化一致，这表明在压力热环境中对mtDNA的自然选择在性别上是一致的。我们讨论了我们的发现对mtDNA进化的意义。
