Doctoral Dissertation Improvement: Morphological Integration in Primate Hands and Feet

单灵长类动物（类人猿和猴子）的手和脚具有相似的内在比例，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）的手和脚相对于手掌或脚掌有较长的手指，相对较长的第一根手指可以安全地抓住小的树栖支撑物。悬吊的灵长类动物，如长臂猿，通过前肢和后肢的组合悬挂在树的支撑物下，它们的四肢有长而弯曲的指骨。在陆生物种中，数字化四足动物（如木瓜肽）相对于跖骨（掌骨和跖骨）具有短而直的指骨。值得注意的是，即使是人类也有类似比例的四肢，尽管他们的手和脚执行不同的功能。相对于四肢而言，人类的手和脚是短的，有短而强壮的跖骨，短的外侧指骨和相对较长的第一指（大脚趾和拇指）。国家科学基金会的支持将允许Campbell Rolian测试单足动物的手脚骨骼的相似性是否是对相似功能的选择的结果，或者是否潜在的发育现象，如多效性（当一个基因位点影响表型的多个方面时）导致手脚骨骼之间的相关性比骨骼的其他部分更强。手和足发育遗传程序之间的多效效应可能在趾形态的进化中具有潜在的冲突作用。当手和足趾进化到具有相似的运动功能时，多效性应该促进相关形态学的变化。然而，当手和脚的手指进化为独立的功能时，那么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个类群的500多个个体的手和脚的骨骼中收集形态测量数据，这些数据被选中来代表单足动物运动行为的多样性和进化亲缘关系的广度。这些数据将用于比较物种内部和物种之间的表型共变模式，测试关于功能与发育在推动灵长类动物趾形态独立进化中的重要性的假设。意义和更广泛的影响：很少有研究从经验上解决发育限制如何影响形态分化的自然选择。坎贝尔将通过观察单足动物的手和脚的共变来解决这个重要的问题。以灵长类肢体骨骼为例，本项目将为脊椎动物形态进化的模式和过程提供更广泛的见解，特别是因为它们与进化发育生物学（evo-devo）的发展领域有关。这个项目对人类进化的研究也有重要的意义。例如，研究结果可能会提供证据，证明人类的手和脚并不是独立进化出它们固有的比例的。这些信息对于检验关于人类谱系中操纵能力和两足行走的选择性历史的长期假设至关重要。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，以及创建灵长类动物手脚骨骼的宝贵数字档案。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.