Ancient mitogenomes from the Southern Pampas of Argentina reflect local differentiation and limited extra‐regional linkages after rapid initial colonization

Abstract

Objective This study aims to contribute to the recovery of Indigenous evolutionary history in the Southern Pampas region of Argentina through an analysis of ancient complete mitochondrial genomes. Materials and Methods We generated DNA data for nine complete mitogenomes from the Southern Pampas, dated to between 2531 and 723 cal BP. In combination with previously published ancient mitogenomes from the region and from throughout South America, we documented instances of extra‐regional lineage‐sharing, and estimated coalescent ages for local lineages using a Bayesian method with tip calibrations in a phylogenetic analysis. Results We identified a novel mitochondrial haplogroup, B2b16, and two recently defined haplogroups, A2ay and B2ak1, as well as three local haplotypes within founder haplogroups C1b and C1d. We detected lineage‐sharing with ancient and contemporary individuals from Central Argentina, but not with ancient or contemporary samples from North Patagonian or Littoral regions of Argentina, despite archeological evidence of cultural interactions with the latter regions. The estimated coalescent age of these shared lineages is ~10,000 years BP. Discussion The history of the human populations in the Southern Pampas is temporally deep, exhibiting long‐term continuity of mitogenome lineages. Additionally, the identification of highly localized mtDNA clades accords with a model of relatively rapid initial colonization of South America by Indigenous communities, followed by more local patterns of limited gene flow and genetic drift in various South American regions, including the Pampas.

Letter to the editor: A Southern Cone origin rather than Peruvian affinities for ancient Patagonian B2 mitogenomes

“…Arencibia and co-workers stated that PE916 and SAC 1-1-4 "were grouped within a cluster mainly composed of B2b9 haplotypes found in Peruvian individuals,", and that "this cluster also included the mitogenome obtained for the individual LCH.E2-I2.1" (Arencibia, Muñoz, et al, 2023, p. 7). LCH.E2-I2.1 (accession number MW291676) is one out of four ancient mitogenomes spanning about 6000 years recently employed by Motti et al (2023) to establish clade B2b16, whose known distribution so far is restricted to the Argentinean Pampas. Neither the B2b9 individuals nor LCH.E2-I2.1 share synapomorphies beyond B2b with SAC 1-1-4 and thus the author's interpretation of their phylogenetic analysis somehow misrepresents available evidence.…”