Origin and evolution of genes on the human X chromosome

Two groups of functionally related genes are found on the human X chromosome in disproportionately high numbers. I will test whether an uneven distribution of genes is common in mammalian genomes, or whether the human X is special. I will test hypotheses of how the gene groups arose on the human X by comparing their location and expression patterns in other mammals, and other vertebrates. It will then be clear whether the ancestral autosome was chosen , whether it selfishly accumulated these genes, or whether the function of genes changed in response to selective pressures.