Mitocondrial DNA variation on mexican indigenous population from the state of Puebla

Abstract

Mitochondrial adn (mtdna) has been widely used as a genetic marker in studies of phylogeny and human evolution. Its uniparental inheritability allows tracing the divergent maternal lineages among populations, as well as geographic dispersal routes. Dating these events becomes possible with the knowledge of their mutation rate. Variants contained within the genome can be grouped, identifying the occurrence of diagnostic mutations, in what is called haplogoups. In America there are five haplogroups that represent the diversity of our native populations (A, B, C, D and X). For purposes of this study, we analyzed sequences of the hypervariable region I of 50 individuals from two indigenous communities: Totonac and Nahua, both from the Sierra Norte de Puebla. The frequencies of mitochondrial haplogroups in these populations are consistent with those reported previously in wich haplogroup A2 is the most frequent (.74), followed by haplogroup B2 (.20); haplogroup D is present only in the Totonac population but with very low frequency. A higher haplotype diversity in the Nahua group, which may be due to the integration of new variants in mixing processes in this group during the period of the Mexica empire expansion. There is a higher number of polymorphic sites in the Totonac population, which supports historical data that present this population as originating in the region; the higher representation Totonac individuals ancient node in the network of haplogroup A2 supports this proposal.