Department of Biology, University of St. Thomas, St. Paul, MN 55105, USA.
Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
J Exp Biol. 2022 Feb 15;225(Suppl1). doi: 10.1242/jeb.243351. Epub 2022 Feb 4.
Phenotypic trade-offs are inevitable in nature, but the mechanisms driving them are poorly understood. Movement and oxygen are essential to all animals, and as such, the common ancestor to all living animals passed on mechanisms to acquire oxygen and contract muscle, sometimes at the expense of other activities or expression of traits. Nevertheless, convergent pathways have also evolved to deal with critical trade-offs that are necessary to survive ubiquitous environmental challenges. We discuss how whole-animal performance traits, such as locomotion, are important to fitness, yet costly, resulting in trade-offs with other aspects of the phenotype via specific conserved and convergent mechanistic pathways across all animals. Specifically, we discuss conserved pathways involved in muscle structure and signaling, insulin/insulin-like signaling, sirtuins, mitochondria and hypoxia-inducible factors, as well as convergent pathways involved in energy regulation, development, reproductive investment and energy storage. The details of these mechanisms are only known from a few model systems, and more comparative studies are needed. We make two main recommendations as a framework for future studies of animal form and function. First, studies of performance should consider the broader life-history context of the organism, and vice versa, as performance expression can require a large portion of acquired resources. Second, studies of life histories or mechanistic pathways that measure performance should do so in meaningful and standardized ways. Understanding proximate mechanisms of phenotypic trade-offs will not only better explain the phenotypes of the organisms we study, but also allow predictions about phenotypic variation at the evolutionary scale.
表型权衡在自然界中是不可避免的，但驱动它们的机制却知之甚少。运动和氧气对所有动物都是必不可少的，因此，所有现存动物的共同祖先都遗传了获取氧气和收缩肌肉的机制，有时这是以牺牲其他活动或特征表达为代价的。然而，为了应对生存所必需的普遍环境挑战，也进化出了趋同途径。我们讨论了如何通过整个动物的性能特征（如运动）来提高适应性，而这些特征是有代价的，因此通过特定的保守和趋同的机制途径与表型的其他方面产生权衡。具体来说，我们讨论了涉及肌肉结构和信号、胰岛素/胰岛素样信号、沉默信息调节因子、线粒体和缺氧诱导因子的保守途径，以及涉及能量调节、发育、生殖投资和能量储存的趋同途径。这些机制的细节仅从少数模式系统中得知，还需要更多的比较研究。我们提出了两个主要建议，作为未来研究动物形态和功能的框架。首先，性能研究应考虑到生物体更广泛的生活史背景，反之亦然，因为性能表达可能需要大量获得的资源。其次，测量性能的生活史或机制途径的研究应以有意义和标准化的方式进行。了解表型权衡的近似机制不仅可以更好地解释我们研究的生物体的表型，还可以预测进化尺度上的表型变异。
