mtDNA diversity of the Zapotec in Mexico suggests a population decline long before the first contact with Europeans.

The New World is the last continent colonized by anatomically modern humans, Homo sapiens. The first migrants entered the New World from Asia through Beringia. It is suggested that there were three streams of Asian gene flow, one major and two additional minor gene flows. The first major migrants took a Pacific coastal route and began spreading to the American continent before the opening of the ice-free corridor. We investigated the diversity of full-length mitochondrial DNA genomes of the Zapotec population, residing in the Mesoamerican region, and reconstructed their demographic history using Bayesian Skyline Plots. We estimated the initial date of gene flow into the New World by Zapotec ancestors at around 17 000–19 000 years ago,which is highly concordant with previous studies. We also show a population decline after the initial expansion. This decline started 4000 years ago, long before European contact with Native Americans. This indicates that other factors including climatec hange should be considered to explain the observed demographic pattern

Characterization of complete mitochondrial genomes of indigenous Mayans in Mexico

Background: The authors have previously published the complete mitochondrial genome (mitogenome) sequences of two indigenous Mesoamerican populations, Mazahua (n = 25) and Zapotec (n = 88). Methods: This study determined the complete mitogenome sequences of nine unrelated individuals from the indigenous Maya population living in Mexico. Results: Their mitogenome sequences could be classified into either of the haplogroups A2 and C1. Surprisingly, there were no mitogenome sequences (haplotypes) that the Maya, Mazahua, and Zapotec people share in common. Conclusions: This indicates that no genetic exchange, at least matrilineally, has occurred among them

Complete mitogenome analysis of indigenous populations in Mexico: its relevance for the origin of Mesoamericans.

Mesoamerica has an important role in the expansion of Paleoamericans as the route to South America. In this study, we determined complete mitogenome sequences of 113 unrelated individuals from two indigenous populations of Mesoamerica, Mazahua and Zapotec. All newly sequenced mitogenomes could be classified into haplogroups A2, B2, C1 and D1, but one sequence in Mazahua was D4h3a, a subclade of haplogroup D4. This haplogroup has been mostly found in South America along the Pacific coast. Haplogroup X2a was not found in either population. Genetic similarity obtained using phylogenetic tree construction and principal component analysis showed that these two populations are distantly related to each other. Actually, the Mazahua and the Zapotec shared no sequences (haplotypes) in common, while each also showed a number of unique subclades. Surprisingly, Zapotec formed a cluster with indigenous populations living in an area from central Mesoamerica to Central America. By contrast, the Mazahua formed a group with indigenous populations living in external areas, including southwestern North America and South America. This intriguing genetic relationship suggests the presence of two paleo-Mesoamerican groups, invoking a scenario in which one group had expanded into South America and the other resided in Mesoamerica