High Resolution Mitochondrial DNA Analysis Sheds Light On Human Diversity, Cultural Interactions And Population Mobility In Northwestern Amazonia

Abstract

ObjectivesNorthwestern Amazonia (NWA) is a center of high linguistic and cultural diversity. Several language families and linguistic isolates occur in this region, as well as different subsistence patterns: some groups are foragers while others are agriculturalists. In addition, speakers of Eastern Tukanoan languages are known for practicing linguistic exogamy, a marriage system in which partners must come from different language groups. In this study, we use high resolution mitochondrial DNA sequencing to investigate the impact of this linguistic and cultural diversity on the genetic relationships and structure of NWA groups.\n\nMethodsWe collected saliva samples from individuals representing 40 different NWA ethnolinguistic groups and sequenced 439 complete mitochondrial genomes to an average coverage of 1030x.\n\nResultsThe mtDNA data revealed that NWA populations have high genetic diversity with extensive sharing of haplotypes among groups. Moreover, groups who practice linguistic exogamy have higher mtDNA diversity, while the foraging Nukak have lower diversity. We also find that rivers play a more important role than either geography or language affiliation in structuring the genetic relationships of populations.\n\nDiscussionContrary to the view of NWA as a pristine area inhabited by small human populations living in isolation, our data support a view of high diversity and contact among different ethnolinguistic groups; movement along rivers has probably facilitated this contact. Additionally, we provide evidence for the impact of cultural practices, such as linguistic exogamy, on patterns of genetic variation. Overall, this study provides new data and insights into a remote and little-studied region of the world.