A revised root for the human Y chromosome differentiation and diversity landscape among North African populations

Abstract

The Y chromosome has a curious role in population Genetics and forensic genetics. It is male specific and constitutively haploid. It passes from father to son, and, unlike other chromosomes, largely escapes meiotic recombination. Two segments (the pseudoautosomal regions) do recombine with the X, but this amount to less than 3 Mb of its ~60-Mb length, which makes it easier to study than the autosomes.1 These traits, explains its use in an increasing number of studies, especially those that address the history of the human population and makes it easier to study than the autosomes. Nevertheless, the Y chromosome continues to be overshadowed in these studies by the autosomal chromosome and mtDNA, despite containing far more genetic information than either. One reason for the lagging position of the Y chromosome has been a delay in the generation of useful data. The first PHYLOGENETIC TREE for human mtDNA was published in 1987,2 and the first for the Y chromosome was published in 1989.3 Since then, Y-chromosome-based studies have slowly accumulated; with the maturation of sequencing and genotyping technologies, a tremendous increase in all kinds of genetic data looms. It is therefore an appropriate time to reflect on what the Y chromosome can offer to population-genetic studies.