Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland.
Univ Lyon, Université Claude Bernard Lyon 1, UMR 5023 LEHNA, CNRS, ENTPE, Villeurbanne, France.
Proc Biol Sci. 2022 Jul 13;289(1978):20220719. doi: 10.1098/rspb.2022.0719.
Intra-specific variation in both the basal metabolic rate (BMR) and mitochondrial efficiency (the amount of ATP produced per unit of oxygen consumed) has profound evolutionary and ecological consequences. However, the functional mechanisms responsible for this variation are not fully understood. Mitochondrial efficiency is negatively correlated with BMR at the interspecific level but it is positively correlated with performance capacity at the intra-specific level. This discrepancy is surprising, as theories explaining the evolution of endothermy assume a positive correlation between BMR and performance capacity. Here, we quantified mitochondrial oxidative phosphorylation activity and efficiency in two lines of laboratory mice divergently selected for either high (H-BMR) or low (L-BMR) levels of BMR. H-BMR mice had larger livers and kidneys (organs that are important predictors of BMR). H-BMR mice also showed higher oxidative phosphorylation activity in liver mitochondria but this difference can be hypothesized to be a direct effect of selection only if the heritability of this trait is low. However, mitochondrial efficiency in all studied organs did not differ between the two lines. We conclude that the rapid evolution of BMR can reflect changes in organ size rather than mitochondrial properties, and does not need to be accompanied obligatorily by changes in mitochondrial efficiency.
种内变异在基础代谢率（BMR）和线粒体效率（每单位耗氧量产生的 ATP 量）方面具有深远的进化和生态后果。然而，导致这种变异的功能机制尚未完全了解。线粒体效率在种间水平上与 BMR 呈负相关，但在种内水平上与性能能力呈正相关。这种差异令人惊讶，因为解释恒温动物进化的理论假设 BMR 与性能能力之间存在正相关。在这里，我们在两条实验室小鼠品系中量化了线粒体氧化磷酸化活性和效率，这两条品系分别为高（H-BMR）或低（L-BMR）水平的 BMR 进行了选择。H-BMR 小鼠的肝脏和肾脏较大（这些器官是 BMR 的重要预测因子）。H-BMR 小鼠的肝脏线粒体中也显示出更高的氧化磷酸化活性，但如果该性状的遗传力较低，则可以假设这种差异只是选择的直接结果。然而，两条品系之间的所有研究器官的线粒体效率没有差异。我们得出结论，BMR 的快速进化可以反映器官大小的变化，而不是线粒体特性的变化，并且不一定需要伴随着线粒体效率的变化。
