Natural selection and the evolution of the invasive trophoblast in hominoid primates
Bayer School of Natural and Environmental Sciences
Brady A. Porter
David J. Lampe
ECM, Evolution, Ka/Ks, MMP, Placenta, Reproduction, TIMP
Humans and apes (hominoids) differ from Old World monkeys (OWMs) in the depth of placental trophoblast invasion. OWMs have a superficial placentation, with little invasion of the trophoblast into the uterine endometrium, while hominoids, and humans in particular, have a more invasive trophoblast, allowing for increased blood flow and nutrients to the developing fetus. This dramatic, morphological change, occurring on the hominoid stem branch and human lineage, may be explained by positive selection of genes involved in trophoblast implantation, resulting in the origin of the invasive trophoblast. Comparative sequencing of cell adhesion molecules, proteinases, and proteinase inhibitors involved in trophoblast implantation, in representative OWM and hominoid species, revealed uniform, purifying selection, with little differences between the hominoid stem branch, the human lineage, and the rest of the tree, suggesting that positive selection on these genes alone may not account for the phenotypic differences between humans and our primate relatives.
Litman, P. (2006). Natural selection and the evolution of the invasive trophoblast in hominoid primates (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/1632