Doctoral Dissertation Improvement: Morphological Integration in Primate Hands and Feet

单目灵长类动物(类人猿和猴子)的手和脚具有相似的固有比例，这往往与它们的栖息地和运动方式有关。例如，树栖四足动物(如新大陆猴子)的手脚相对于手掌或脚掌有较长的指头，第一个指头相对较长，能够牢牢抓住树生动物的小支撑物。悬垂灵长类动物，如长臂猿，通过前肢和后肢的组合悬挂在树栖支撑物的下方，它们的四肢有又长又弯曲的指骨。在陆生物种中，数字化的四足动物(如鹦鹉)相对于后足(掌骨和跖骨)有短而直的指骨。值得注意的是，即使人类也有相似比例的四肢，尽管他们的手和脚执行不同的功能。人类的手和脚相对于四肢来说很短，有短而结实的后趾，短的外侧指骨和按比例较长的第一个指头(大拇指和脚趾)。美国国家科学基金会的支持将使Campbell Rolian能够测试，单亲人类手和脚之间的骨骼相似性是否是相似功能选择的结果，或者是潜在的发育现象，如多效性(当一个基因位点影响表型的多个方面)是否会导致手和脚的骨骼彼此之间的相关性比骨骼的其他部分更强。手和脚发育遗传程序之间的多效性效应可能在手指形态的进化中具有潜在的冲突作用。当手和脚的手指进化到执行相似的运动功能时，多效性应该有助于相关的形态变化。然而，当手和脚的手指进化为执行不同的功能时，多效性效应可能会限制手和脚的数字形状的独立进化。坎贝尔将从13个分类群的500多个个体的手部和脚部骨骼中收集形态测量数据，这些数据被选为代表单亲动物运动行为的多样性和进化联系的广度。这些数据将被用来比较物种内和物种之间的表型协变模式，测试关于功能和发育在推动灵长类动物手指形态独立进化中的重要性的假设。意义和更广泛的影响：很少有研究经验性地研究发育限制如何使自然选择偏向于形态差异。坎贝尔将通过观察单臂的手和脚的协变来解决这个重要的问题。以灵长类肢体骨骼为例，该项目将为脊椎动物形态进化的模式和过程提供更广泛的洞察力，特别是当它们与不断增长的进化发育生物学(EVO-DEVO)领域相关时。该项目对人类进化的研究也具有重要意义。例如，结果可能会提供证据，证明人类的手和脚并没有独立地进化出它们固有的比例。这些信息将对检验长期存在的关于原始人血统中操纵能力和两足动物的选择性历史的假说至关重要。这项研究的其他更广泛的影响包括为本科教育提供教学工具，以及创建一个有价值的灵长类手脚骨骼数字档案。通过在同行评议的期刊上发表文章和在跨学科会议上发表演讲，该项目还将有助于将体质人类学的研究生培训和研究与进化发育生物学结合起来。

The hands and feet of haplorhine primates (apes and monkeys) have similar intrinsic proportions that tend to correlate with their habitat and mode of locomotion. For example, arboreal quadrupeds (e.g. New World monkeys) have hands and feet with long digits in relation to the palm or sole, and a relatively long first digit enabling a secure grasp on small arboreal supports. Suspensory primates such as gibbons hang below arboreal supports by combinations of forelimbs and hindlimbs, and their extremities have long, curved phalanges. Among terrestrial species, digitigrade quadrupeds (e.g. papionins) have short straight phalanges relative to the metapodials (metacarpals and metatarsals). Remarkably, even humans have similarly proportioned extremities, despite the fact that their hands and feet perform different functions. Human hands and feet are short in relation to the limbs, with short, robust metapodials, short lateral phalanges and a proportionately longer first digit (great toe and thumb). NSF support will allow Campbell Rolian to test whether these skeletal similarities between hands and feet in haplorhines are the result of selection for similar functions, or whether underlying developmental phenomena such as pleiotropy (when one gene locus affects multiple aspects of the phenotype) cause hand and foot bones to be more strongly correlated with each other than with other parts of the skeleton. Pleiotropic effects between hand and foot developmental genetic programs can have potentially conflicting roles in the evolution of digit morphology. When hand and foot digits evolve to perform similar locomotor functions, pleiotropy should facilitate correlated changes in morphology. However, when hand and foot digits evolve to perform separate functions, then pleiotropic effects may constrain the independent evolution of digital shape in the hands and feet. Campbell will collect morphometric data from the bones of the hands and feet of over 500 individuals from 13 taxa, selected to represent the diversity of locomotor behaviors and breadth of evolutionary relatedness among haplorhines. These data will be used to compare patterns of phenotypic covariation within and between species, testing hypotheses about the importance of function vs development in driving the independent evolution of digit morphology in primates.Significance and Broader Impacts: Few studies have addressed empirically how developmental constraints may bias natural selection for morphological divergence. Campbell will address this important question by looking at covariation in haplorhine hands and feet. Using primate limb skeletons as a case study, this project will provide broader insight into the patterns and processes of vertebrate morphological evolution, particularly as they relate to the growing field of evolutionary developmental biology (evo-devo). This project also has important implications for the study of human evolution. For instance, results may provide evidence that human hands and feet did not evolve their intrinsic proportions independently. Such information will be critical for testing long-standing hypotheses about the selective history of manipulative ability and bipedalism in the hominin lineage. Additional broader impacts of the study include providing teaching tools for undergraduate education, and the creation of a valuable digital archive of primate hand and foot skeletons. Through publications in peer reviewed journals and presentations at interdisciplinary conferences, this project will also help integrate graduate training and research in physical anthropology with evolutionary developmental biology.