Collaborative Research: The Evolutionary Interplay Between Life-Histories, Morphology, Performance, and Behavior in Trinidad Guppies

自然选择进化论，或适应原理，是查尔斯·达尔文提出的进化论机制。达尔文认为，适应是生物体的任何特征，是自然选择的结果，并增强了个体的生存和繁殖潜力。然而，理解和实证记录似乎具有适应性的特定特征与选择用于该特征进化的因素之间的关系仍然是一项具有挑战性和争议性的任务。自达尔文以来，从自然选择的经验研究中学到的主要教训是，适应很少孤立地发生，而是受到其他相互作用特征的功能的制约，最终是有机体的综合方面之间的妥协。因此，对适应的研究需要了解不同的性状是如何相互制约的，以及它们是如何整合在一起产生局部适应的表型的。只有有限的经验证据表明，这些限制是如何在真实生物体中表现出来的。这项拟议的工作将研究选择如何作用于孔雀鱼自然种群的生殖策略、体型、游泳表现和行为的整合。孔雀鱼是这项拟议工作的模式生物，因为它是为数不多的适应被记录在案的生物之一。这项先前的工作表明孔雀鱼的生殖特征对捕食性鱼类的反应发生了快速的适应性变化。这里提出的工作将首先记录生殖特征、身体形态、栖息地利用、觅食行为和溪流类型之间的相关性，并对来自不同选择压力的种群的雌性和雄性孔雀鱼进行实地观察。它将集中在水流和捕食的综合影响上。由于孔雀鱼的生殖特征已经从这些地点得知，所获得的形态和行为结果将提供第一批数据，说明身体形态、觅食行为、栖息地利用和繁殖策略是否可预测地相互变化，或者它们是否随着不同的选择压力而独立变化。然后，孔雀将在不同的环境下在实验室中饲养，以测试种群之间的这些特征差异代表固定遗传差异或表型可塑性的程度。最后，这项拟议的工作将通过测量身体轮廓和游泳性能在生殖周期过程中的变化，首次研究怀孕对水生物种身体形态和运动的影响。来自高捕食区和低捕食区的怀孕雌性的稳定和逃逸游泳行为将测试不同的生殖分配对运动的影响，以及后代数量的适应性变化如何影响运动。通过研究繁殖策略、形态、运动性能和行为如何相互作用并共同应对不同的选择压力，拟议的工作将提供更好的理解，以了解活着的鱼类在适应当地环境时所面临的权衡。

Evolution by natural selection, or the principle of adaptation, was Charles Darwin's proposed mechanism for evolution. Darwin viewed an adaptation as any feature of an organism that arose as consequence of natural selection and enhanced the survival and reproductive potential of the individual. Yet, understanding and empirically documenting the relationship between a particular trait that appears to be adaptive and the factors that selected for the evolution of the trait remains a challenging and controversial task. In the time since Darwin, the main lessons learned from empirical studies of natural selection are that adaptations rarely occur in isolation, but rather are constrained by the function of other interacting traits, and are a ultimately a compromise between integrated aspects of the organism. Accordingly, the study of adaptation requires an understanding of how different traits constrain each other and how they are integrated to produce locally adapted phenotypes. There is only limited empirical evidence for how such constraints are manifested in real organisms. The proposed work will examine how selection acts on the integration of reproductive strategies, body shape, swimming performance, and behavior in natural populations of the guppy, Poecilia reticulata. The guppy is a model organism for the proposed work because it is one of the few organisms where adaptation has been documented. This previous work shows rapid adaptive changes in the reproductive traits of guppies in response to predatory fish. The work proposed here will first document the correlations among reproductive traits, body morphology, habitat use, foraging behavior, and stream type with field observations on female and male guppies from populations that are subject to different selection pressures. It will focus on the combined influences of stream current and predation. Because the reproductive traits of guppies are already known from these sites, the morphological and behavioral results obtained will provide the first data on whether body morphology, foraging behavior, habitat use, and reproductive strategies predictably covary with each other, or whether they vary independently in response to different selection pressures. Guppies will then be reared in the lab under different environments to test the degree to which these trait differences between populations represent fixed genetic differences or phenotypic plasticity. Finally, the proposed work will examine for the first time the consequences of pregnancy on body morphology and locomotion in an aquatic species by measuring how body profile and swimming performance change over the course of the reproductive cycle. Steady and escape swimming performance of gravid females from high and low predation localities will test the consequences of different reproductive allotments on locomotion and how adaptive changes in offspring number may compromise locomotion. By studying how reproductive strategies, morphology, locomotor performance, and behavior interact with each other and collectively respond to different selection pressures, the proposed work will provide a better understanding of the trade-offs faced by live-bearing fish adapting to their local environments.