Mitochondrial function is critical for energy homeostasis and should shape how genetic variation in metabolism is transmitted through levels of biological organization to generate stability in organismal performance. Mitochondrial function is encoded by genes in two distinct and separately inherited genomes - the mitochondrial genome and the nuclear genome - and selection is expected to maintain functional mito-nuclear interactions. The documented high levels of polymorphism in genes involved in these mito-nuclear interactions and wide variation for mitochondrial function demands an explanation for how and why variability in such a fundamental trait is maintained. Potamopyrgus antipodarum is a New Zealand freshwater snail with coexisting sexual and asexual individuals and, accordingly, contrasting systems of separate vs. co-inheritance of nuclear and mitochondrial genomes. As such, this snail provides a powerful means to dissect the evolutionary and functional consequences of mito-nuclear variation. The lakes inhabited by P. antipodarum span wide environmental gradients, with substantial across-lake genetic structure and mito-nuclear discordance. This situation allows us to use comparisons across reproductive modes and lakes to partition variation in cellular respiration across genetic and environmental axes. Here, we integrated cellular, physiological, and behavioral approaches to quantify variation in mitochondrial function across a diverse set of wild P. antipodarum lineages. We found extensive across-lake variation in organismal oxygen consumption and behavioral response to heat stress and differences across sexes in mitochondrial membrane potential but few global effects of reproductive mode. Taken together, our data set the stage for applying this important model system for sexual reproduction and polyploidy to dissecting the complex relationships between mito-nuclear variation, performance, plasticity, and fitness in natural populations.

中文翻译：

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新西兰蜗牛种群线粒体相关性能特征的表型变异

线粒体功能对于能量稳态至关重要，应该塑造代谢中的遗传变异如何通过生物组织水平传递以产生生物体性能的稳定性。线粒体功能由两个不同且单独遗传的基因组中的基因编码 - 线粒体基因组和核基因组 - 并且选择有望维持功能性线粒体 - 核相互作用。已记录的参与这些线粒体核相互作用的基因的高水平多态性和线粒体功能的广泛变异需要解释如何以及为什么保持这种基本特征的变异性。Potamopyrgus antipodarum 是一种新西兰淡水蜗牛，有性个体和无性个体共存，因此，分离与无性个体形成对比系统。核和线粒体基因组的共同遗传。因此，这种蜗牛提供了一种强大的手段来剖析线粒体核变异的进化和功能后果。P. antipodarum 栖息的湖泊跨越了广泛的环境梯度，具有大量的跨湖遗传结构和线粒体核不一致。这种情况使我们能够使用生殖模式和湖泊之间的比较来划分遗传和环境轴上细胞呼吸的变化。在这里，我们整合了细胞、生理和行为方法来量化一组不同的野生 P. antipodarum 谱系中线粒体功能的变化。我们发现生物体耗氧量和对热应激的行为反应以及线粒体膜电位的性别差异存在广泛的跨湖变化，但生殖模式的全球影响很少。总之，我们的数据为应用这一重要的有性生殖和多倍体模型系统来剖析自然种群中的线粒体核变异、性能、可塑性和适应性之间的复杂关系奠定了基础。