School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
Institute for Comparative Genomics and Richard Gilder Graduate School, American Museum of Natural History, New York, New York, USA.
Mol Ecol. 2024 Jun;33(12):e17374. doi: 10.1111/mec.17374. Epub 2024 May 10.
Understanding genetic incompatibilities and genetic introgression between incipient species are major goals in evolutionary biology. Mitochondrial genes evolve rapidly and exist in dense gene networks with coevolved nuclear genes, suggesting that mitochondrial respiration may be particularly susceptible to disruption in hybrid organisms. Mitonuclear interactions have been demonstrated to contribute to hybrid dysfunction between deeply divergent taxa crossed in the laboratory, but there are few empirical examples of mitonuclear interactions between younger lineages that naturally hybridize. Here, we use controlled hybrid crosses and high-resolution respirometry to provide the first experimental evidence in a bird that inter-lineage mitonuclear interactions impact mitochondrial aerobic metabolism. Specifically, respiration capacity of the two mitodiscordant backcrosses (with mismatched mitonuclear combinations) differs from one another, although they do not differ significantly from the parental groups or mitoconcordant backcrosses as we would expect of mitonuclear disruptions. In the wild hybrid zone between these subspecies, the mitochondrial cline centre is shifted west of the nuclear cline centre, which is consistent with the direction of our experimental results. Our results therefore demonstrate asymmetric mitonuclear interactions that impact the capacity of cellular mitochondrial respiration and may help to explain the geographic discordance between mitochondrial and nuclear genomes observed in the wild.
了解初生种间的遗传不相容性和遗传渐渗是进化生物学的主要目标。线粒体基因进化迅速，与共进化的核基因存在密集的基因网络，这表明线粒体呼吸可能特别容易受到杂交生物的破坏。已经证明，线粒体-核相互作用有助于实验室中深度分化的分类群之间的杂种功能障碍，但在自然杂交的年轻谱系之间很少有关于线粒体-核相互作用的经验实例。在这里，我们使用受控的杂交交叉和高分辨率呼吸测量法，首次在鸟类中提供了种间线粒体-核相互作用影响线粒体需氧代谢的实验证据。具体来说，两个线粒体不和谐的回交（具有不匹配的线粒体-核组合）的呼吸能力彼此不同，尽管它们与亲本群体或线粒体和谐回交没有显著差异，这是我们预期的线粒体破坏的结果。在这些亚种之间的野生杂交区，线粒体渐变中心位于核渐变中心的西部，这与我们的实验结果一致。因此，我们的结果表明存在不对称的线粒体-核相互作用，这影响细胞线粒体呼吸的能力，并可能有助于解释在野外观察到的线粒体和核基因组之间的地理不协调性。
