Doctoral Dissertation Improvement: Investigating the Obstetrical Dilemma: Patterns of Morphological Integration in the Primate Pelvis

现代人的生育是所有现存的类人猿中最困难的，人们认为这是后来古人类两种相互竞争的选择力量之间妥协的结果：一种是允许有效的双足运动，另一种是允许分娩出一个大脑袋、大身体的后代——“产科困境”。过去的研究通过比较古人类和其他类人猿的骨盆特征的方式和比例来支持这一假设，这些差异被认为是过去的选择压力对不同功能需求的结果。此外，性状之间的相关性（即整合模式）也可能对选择作出反应，因此分析盆腔整合模式的种间差异为解决这一进化问题提供了新的途径。该项目使用进化定量方法来检验关于两足动物和产科学的选择压力在古人类骨盆形态进化中所起作用的假设。它将重建古人类骨盆中过去的选择压力，并定量确定两足动物和产科学的压力在导致古人类物种形态变化中所起的作用。这项研究揭示了被认为是适应两足行走或分娩的特征是否实际上是对其他特征选择的相关反应，而不是选择的直接产物。最后，该研究测试了人类骨盆的整合模式是否在与产科困境相关的相互冲突的选择压力下进化而来，以及这些模式在人类骨盆形态的进化中发挥了什么作用。除了进一步了解两足直立行走和生下大脑量婴儿之间权衡的进化困境之外，该项目还将进一步加强联合pi在基于进化遗传学、生物学、统计学和生物人类学的跨学科方法方面的培训，这可能为进化生物学中与大规模适应中整合模式的作用有关的更广泛问题提供数据。以及它们促进进化变化的能力。对本科生的指导也有很多途径，使他们能够参与不同层次的分析，并提供进行科学研究的实践经验。

Modern human birth is the most difficult of any living great ape, and is believed to be the result of a compromise between two competing selective forces in later hominins: one to allow for efficient obligate bipedal locomotion, and one to permit parturition of a large-brained and large-bodied offspring - the "obstetrical dilemma." Past studies have supported this hypothesis through analyses which compare means and proportions of pelvic traits between hominins and other apes, differences that are believed to be the result of past selection pressures for divergent functional requirements. In addition, correlations between traits (i.e. patterns of integration) may also respond to selection, and thus analyzing interspecific differences in pelvic patterns of integration provides a new route to addressing this evolutionary problem. This project uses evolutionary quantitative methods to test hypotheses about the roles that selection pressures for bipedalism and obstetrics have played in the evolution of hominin pelvic morphology. It will reconstruct past selection pressures in the pelves of hominins and quantitatively determine the roles that pressures for bipedalism and obstetrics played in causing the morphological changes seen across species of hominins. The research reveals if traits thought to be adaptations for bipedalism or parturition are actually correlated responses to selection on other traits rather than having been direct products of selection. Finally, the research tests if patterns of integration in the pelves of humans have evolved in response to conflicting selection pressures relating to the obstetrical dilemma and what role these patterns have played in the evolution of hominin pelvic morphology. In addition to furthering understanding of the evolutionary dilemma of the trade-offs between walking upright bipedally and giving birth to large-brained infants, this project will further the co-PI's training in an interdisciplinary approach based in evolutionary genetics, biology, statistics, and biological anthropology, which may provide data on broader questions in evolutionary biology relating to the role of patterns of integration in large-scale adaptations, as well as their ability to facilitate evolutionary change. There are also many avenues for the mentoring of undergraduates, allowing them to participate in different levels of analyses and providing hands-on experience in conducting science.