Population History and Gene Divergence in Native Mexicans Inferred from 76 Human Exomes

Area of Science:

• Genomics
• Population Genetics
• Human Evolution

Background:

• Native American genetic diversity is underrepresented in current human genome databases.
• Indigenous Mexican populations exhibit significant genetic differentiation and substructure.
• These populations may possess unique genetic variants with biomedical importance.

Purpose of the Study:

• To characterize the coding genome variation in five Indigenous Mexican populations.
• To model the demographic history of these populations.
• To identify genes under positive selection.

Main Methods:

• Whole-exome sequencing of 76 individuals from five Indigenous Mexican groups.
• Analysis of the full site frequency spectrum.
• Demographic modeling using diffusion approximations.
• Selection scans to detect adaptive evolution.

Main Results:

• Demographic modeling indicated a split between northern and southern groups 7.2 KYA, with subsequent local divergence.
• Positive selection scans identified BCL2L13 in Rarámuris and KBTBD8 in Triquis.
• BCL2L13 may relate to physical endurance in Rarámuris; KBTBD8 is associated with short stature in Triquis.

Conclusions:

• Indigenous Mexican populations harbor unique genetic variation.
• Specific genes show evidence of local adaptation, potentially explaining phenotypic differences.
• This research underscores the importance of including underrepresented populations in genomic studies.