Trade-Offs (and Constraints) in Organismal Biology
Trade-Offs (and Constraints) in Organismal Biology
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DOI：
10.1086/717897
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发表时间：
2022-01-01
影响因子：
1.6
通讯作者：
Ives, Anthony R.
中科院分区：
文献类型：
--
作者：
Garland, Theodore;Downs, Cynthia J.;Ives, Anthony R.
权衡和限制是生命所固有的，对这些现象的研究在生物体生物学和进化生物学中都发挥着核心作用。可以通过至少六种不相互排斥的方式来定义、分类和研究权衡。(1)分配限制是由有限的资源(例如，能量、时间、空间、基本营养)造成的，因此增加对一个组成部分的分配必然需要减少另一个组成部分(如果只涉及两个组成部分，这被称为Y模型，例如，用于大小和后代数量的能量)。(2)当增强一个任务的性能的特征降低了另一个任务的性能时(例如，内杠杆和外杠杆的相对长度、与肌肉纤维类型组成有关的力-速度权衡)，就会发生功能冲突。(3)通常涉及整合分子(如激素、神经递质、转录因子)的共享生化途径可以同时影响多个性状，其中一些影响有利于达尔文适合度的一个或多个组成部分(例如，存活率、首次生育年龄、繁殖力)，而其他影响则是有害的。(4)拮抗多效性描述了增加一个适应度成分(或较低水平的性状)同时降低另一个适应度成分的遗传变异。(5)生态环境(或选择性制度)可能会施加权衡，例如当觅食行为增加能量可获得性但也降低存活率时。(6)性选择可能导致第二性征(通常是男性)的细化，这些第二性征可以提高交配成功，但阻碍生存和/或施加能量成本，从而减少其他健康成分。权衡的经验研究通常寻找两个性状之间的负相关性，这是权衡的预期结果，但如果涉及两个以上的性状，尤其是复杂的相互作用性状的生理网络，这通常是不够的。此外，权衡往往只发生在经历恶劣环境条件或在表型分布极端的能量挑战的种群中，例如在具有特殊运动能力的个体或物种之间。根据所涉及的时间范围，从急性到渐进性，可以通过各种补偿机制(部分)规避权衡。展望未来，对权衡和限制的多元化观点，结合跨越生物组织水平和学科之间传统边界的综合分析，将加强进化生物生物学的研究。
Trade-offs and constraints are inherent to life, and studies of these phenomena play a central role in both organismal and evolutionary biology. Trade-offs can be defined, categorized, and studied in at least six, not mutually exclusive, ways. (1) Allocation constraints are caused by a limited resource (e.g., energy, time, space, essential nutrients), such that increasing allocation to one component necessarily requires a decrease in another (if only two components are involved, this is referred to as the Y-model, e.g., energy devoted to size versus number of offspring). (2) Functional conflicts occur when features that enhance performance of one task decrease performance of another (e.g., relative lengths of in-levers and out-levers, force-velocity trade-offs related to muscle fiber type composition). (3) Shared biochemical pathways, often involving integrator molecules (e.g., hormones, neurotransmitters, transcription factors), can simultaneously affect multiple traits, with some effects being beneficial for one or more components of Darwinian fitness (e.g., survival, age at first reproduction, fecundity) and others detrimental. (4) Antagonistic pleiotropy describes genetic variants that increase one component of fitness (or a lower-level trait) while simultaneously decreasing another. (5) Ecological circumstances (or selective regime) may impose trade-offs, such as when foraging behavior increases energy availability yet also decreases survival. (6) Sexual selection may lead to the elaboration of (usually male) secondary sexual characters that improve mating success but handicap survival and/or impose energetic costs that reduce other fitness components. Empirical studies of trade-offs often search for negative correlations between two traits that are the expected outcomes of the trade-offs, but this will generally be inadequate if more than two traits are involved and especially for complex physiological networks of interacting traits. Moreover, trade-offs often occur only in populations that are experiencing harsh environmental conditions or energetic challenges at the extremes of phenotypic distributions, such as among individuals or species that have exceptional athletic abilities. Trade-offs may be (partially) circumvented through various compensatory mechanisms, depending on the timescale involved, ranging from acute to evolutionary. Going forward, a pluralistic view of trade-offs and constraints, combined with integrative analyses that cross levels of biological organization and traditional boundaries among disciplines, will enhance the study of evolutionary organismal biology.