Abstract

The extremely tight fit between fetal head and maternal pelvic canal during childbirth is a cause of high mortality in humans. However, the relatively narrow size of the female pelvis, evolved for efficient bipedal locomotion, shows morphological covariation with head size, a highly heritable trait. This covariation is thought to reduce the risk of cephalo-pelvic mismatch and obstructed labour1. Morphological covariation arises through the evolution of mechanisms that mediate the coordinated development of functionally related characters2. Hybridization often reduces the degree of morphological integration between characters via genetic introgression3. My research investigates how hybridization in mice influences morphological covariation between skull and pelvis in relation to obstructed labour. After quantifying skull and pelvic shape in different wild mice species and their hybrids, I test the change in their degree and patterns of shape covariation, especially focusing on obstetric-relevant aspects of the pelvis and skull.