DISSERTATION RESEARCH: Comparative Analysis of the Costs of Sexually Selected Traits within Swordtails and Platyfish

小西奥多加兰和Christopher E. OufieroProposal #0709788剑尾鱼和扁尾鱼性选择特征代价的比较分析通过自然选择，生物体通常会随着一代又一代的繁衍而更好地适应环境。 然而，有些性状很难解释为自然选择的结果。 例如，雄性孔雀长而华丽的尾巴似乎会阻碍它们的飞行能力，并吸引捕食者的注意。 此外，这种精心制作的尾巴的生长和维护成本可能很高，将稀缺的能量资源从其他需求中转移出来。 因此，查尔斯·达尔文提出了性选择理论，认为雄性孔雀的尾巴等特征可能会进化，因为它们有助于它们的拥有者获得配偶，即使它们在某种程度上也会牺牲它们必须做的其他事情。 这项研究将探讨成本和潜在的补偿机制，一个良好的描述性选择的特点，“剑”表现出的男性在几个物种的剑尾鱼和比目鱼（属剑尾鱼）。 剑有可能通过增加阻力或生理负担来降低运动能力。 几个运动性能将被检查，包括短跑速度和游泳耐力。 此外，还将检查潜在的代偿特征，如心脏质量和最大耗氧量。 如果不考虑这些特征，这些特征可能会掩盖性选择特征对运动性能的负面影响。 这项研究将大大促进我们对性选择成本的理解。 这将是第一个多物种比较研究，以审查成本和可能的补偿机制。 它也将进一步阐明一个新的脊椎动物系统的结构和性能之间的关系。 这将使生物医学为导向的本科生助理获得更广泛的理解和欣赏，动物行为和有机体生物学，以及这些如何与解剖学和生理学相结合。

Theodore Garland, Jr. and Christopher E. OufieroProposal # 0709788Comparative analysis of the costs of sexually selected traits within swordtails and platyfish.Through natural selection, organisms generally become better adapted to their environmental circumstances with each passing generation. However, some traits are difficult to explain as a result of natural selection. For example, the long and gaudy tails of male peacocks would seem likely to hinder their flying abilities and to attract the attention of predators. Moreover, such elaborate tails are probably expensive to grow and maintain, diverting scarce energetic resources away from other needs. Therefore, Charles Darwin proposed the theory of sexual selection, the idea that such traits as male peacock tails might evolve because they helped their bearers to obtain mates, even if they also compromised, to some extent, other things they had to do. This research will examine costs and potential compensatory mechanisms related to a well-described sexually selected trait, the "sword" exhibited by males in several species of swordtail and platyfish (genus Xiphophorus). The sword has the potential to reduce locomotor abilities through an increase in drag or physiological burden. Several locomotor performances will be examined, including sprint speed and swimming endurance. Additionally, potential compensatory traits, such as heart mass and maximum oxygen consumption, will be examined. When not taken into account, these traits may mask the negative effect of the sexually selected trait on locomotor performance. This research will significantly advance our understanding of the costs of sexual selection. It will be the first multi-species comparative study to examine both costs and possible compensatory mechanisms. It will also further elucidate the relations between structure and performance in a novel vertebrate system. This will enable biomedically oriented undergraduate assistants to gain a broader understanding of, and appreciation for, animal behavior and organismal biology, and how these integrate with anatomy and physiology.