Importance of the geographic barriers to promote gene drift and avoid pre‐ and post‐Columbian gene flow in Mexican native groups: Evidence from forensic STR Loci

Abstract

Different dynamics of gene flow and drift were observed among Mexican Native groups, highlighting the geographic barriers (mountains, canyons and jungle regions) as the main factor differentiating Pre-Hispanic populations, and eventually helping to avoid Post-European contact admixture and population bottleneck. Am J Phys Anthropol 160:298-316, 2016. © 2016 Wiley Periodicals, Inc.

Statistical Parameters of Forensic Importance for 15 Autosomal STRs in Mestizo Population from the State of Guerrero (South Mexico)

“…These contradictory results suggest that Mexican population relationships have been explained by factors such as socioeconomic conditions and educational status associated with the higher European ancestry. 12 Similarly, the IBD hypothesis has not been followed for the study of Native American populations from Mexico when geographic distances are lesser than 1500 km, 13 which is in agreement with our results. A different quadrant of the MDS plot represents the populations of Chihuahua (North) and Jalisco (West), whereas the Yucatan population is isolated in a third different section of the plot (Figure 2).…”

Demographic processes of the Mexican population from X-STRs included in the Investigator Argus X-12 Kit

“…On the other hand, a second Native American ancestry was evident in all Mexican groups, but it was particularly frequent in Huicholes (K ≥ 4), andas expectedit was almost absent in the European references. Similar findings were described with aSTRs in Huicholes and neighboring populations [6]. We estimated the admixture proportions in Mestizo populations, which were compared with those from different genetic systems.…”

“…Among the Native groups, Nahuas and Tarahumaras displayed the highest diversity values, respectively, which could be explained by the larger effective population size (Ne) and European admixture described in these groups [15]. Conversely, the Chiapas pool consistently showed the lowest diversity values, probably as a result of −genetic drift effects helped by the large geographic isolation level of these Native groups, as has been described [6].…”

“…Different genetic diversity parameters were estimated with the program GeneAlEx [8]. In addition, we calculated the theta (&z.Theta;) parameter, which is correlated with the effective population size (Ne) [6]. The program Bottleneck [9] was used to evaluate changes in the demographic size (expansion or reduction).…”

“…Under linguistic criteria they constitute around 90% and 10% of the total Mexican population, respectively. Previous reports with different HID genetic systems, such as autosomal STRs (aSTRs), mitochondrial DNA (mtDNA) and Y-chromosome STRs (YSTRs) have shown a low but significant differentiation among these Mexican populations [3][4][5][6]. In this work, we used available genotype dataset of 12 XSTRs (Investigator Argus X-12, Qiagen) from Mestizo and Native American populations from Mexico to make a deeper analysis of their genetic relationships, structure and admixture.…”