Pre-Columbian male ancestors for the American Continent, molecular Y-chromosome insight

BAILLIET G; MUZZIO M; RAMALLO V; JURADO MEDINA, LS; ALFARO EL; DIPIERRI JE; BRAVI CM

Genetic Diversity / Book 4

In Tech

Año: 2011; p. 291 - 308

It all began back in the 1990’s when the need to compare the mitochondrial DNA for matrilineages arose. It was then when the search for polymorphic markers of the Y-specific region started, in order to test whether the histories of female and male lineages were the same. The human Y chromosome has an intermediate mutational rate between the one from autosomes and the X chromosome. Its mode of inheritance is exclusively patrilinear and its lower effective number (1/4th of the autosomal and 1/3rd regarding the X chromosome) makes it highly susceptible to genetic drift (Jobling and Smith, 2003). Given its specific characteristics, the Y chromosomes have shown some degree of continental differentiation, providing a way of distinguishing among European, American, African, and Asian lineages. A tetranucleotidic microsatellite (DYS19, Roewer et al. 1992), an Alu insert (YAP+ or M1, Hammer et al. 1994), a single nucleotide polymorphism (SNP) (M2) associated to YAP+ (Seielstad et al. 1994), and variants of the alphoid system (Santos et al. 1995) were the first polymorphic systems to be studied. Later on, the fruitful search for polymorphisms led Underhill and collaborators to publish the first phylogeny compiling 166 SNPs geographically correlated (Underhill et al. 2000). Since then the nomenclature was normalized so that different research groups could compare their work (Y Chromosome Consortium, 2002), and an improved phylogeny was published in 2008 by Karafet and collaborators. The accepted phylogeny spans in a tree of 20 major clades that represent haplogroups (Figure 2), where the accumulation of polymorphisms along the lineages determine their diversification and the configuration of sub-branches.