Decrypting the Mitochondrial Gene Pool of Modern Panamanians

Abstract

The Isthmus of Panama–the narrow neck of land connecting the northern and southern American landmasses–was an obligatory corridor for the Paleo-Indians as they moved into South America. Archaeological evidence suggests an unbroken link between modern natives and their Paleo-Indian ancestors in some areas of Panama, even if the surviving indigenous groups account for only 12.3% of the total population. To evaluate if modern Panamanians have retained a larger fraction of the native pre-Columbian gene pool in their maternally-inherited mitochondrial genome, DNA samples and historical records were collected from more than 1500 volunteer participants living in the nine provinces and four indigenous territories of the Republic. Due to recent gene-flow, we detected ∼14% African mitochondrial lineages, confirming the demographic impact of the Atlantic slave trade and subsequent African immigration into Panama from Caribbean islands, and a small European (∼2%) component, indicating only a minor influence of colonialism on the maternal side. The majority (∼83%) of Panamanian mtDNAs clustered into native pan-American lineages, mostly represented by haplogroup A2 (51%). These findings reveal an overwhelming native maternal legacy in today's Panama, which is in contrast with the overall concept of personal identity shared by many Panamanians. Moreover, the A2 sub-clades A2ad and A2af (with the previously named 6 bp Huetar deletion), when analyzed at the maximum level of resolution (26 entire mitochondrial genomes), confirm the major role of the Pacific coastal path in the peopling of North, Central and South America, and testify to the antiquity of native mitochondrial genomes in Panama.

Reconciling migration models to the Americas with the variation of North American native mitogenomes

“…There is some evidence that it might also be present in the Bella Coola tribe (5,44) and among the Ojibwa (5, 45), based solely on the 16111 HVS-I marker. Looking southward, a significant incidence of B2a found in Mexico is confirmed both in tribal groups (42) and general populations (present study), but not in Central America (33,42). Among the two analyzable subclades, defined by a control-region marker (Fig.…”

“…To evaluate this issue, we focused on mitogenomes belonging to two haplogroups, known as A2a and B2a, which are characterized by peculiar geographic distributions. Among the numerous subclades radiating from the root of the panAmerican haplogroup A2 (32)(33)(34), A2a (together with A2b) mtDNAs have been mostly identified only in Siberia, in Alaska, and the surrounding regions, and in Natives from the American Southwest (21,31,(35)(36)(37)(38)(39)(40)(41). B2a radiates from the root of B2, another common pan-American haplogroup.…”

Population History and Mitochondrial Genetic Substructure of the Rama Amerindians from Nicaragua

“…For haplogroup A2 nodes coalesced at 18,000 ± 15,033 YBP (years before present; ρ ± σ = 1.08 ± 0.90). This time estimate falls within the range of other reported dates for haplogroup A2 (Achilli et al 2008;Perego et al 2012;Tamm et al 2007). Contrary to this scenario, haplotypes that belong to the haplogroup B2 coalesced at 1,808 ± 785 YBP (ρ ± σ = 0.10 ± 0.04); however, most recent single mutations emerged around 300 YBP and are more frequent in Rama Cay.…”

“…According to the mtDNA molecular clock, haplogroup A2 most likely coalesced around 18,000 YBP. This estimation falls within the most accepted time of colonization of Central America between 15,000 and 19,000 YBP based on mtDNA (Perego et al 2012).…”

Identification of Whole Mitochondrial Genomes from Venezuela and Implications on Regional Phylogenies in South America

“…Aided by the growing data from whole mitogenomes, the five Native American mtDNA haplogroups initially proposed to be "founder" lineages, A-D and X, have been expanded to at least eight maternal monophyletic haplogroups distributed throughout the Americas: A2, B2, C1b, C1c, C1d, C1d1, D1, and D4h3a (Bandelt et al 2003;de Saint-Pierre et al 2012;Fagundes et al 2008;Perego et al 2009;Tamm et al 2007;Torroni et al 1992). Whole mitogenome studies have further refined the phylogenies of these founding haplogroups and have identified unique lineages within them, among which some appear specific to certain geographical regions (Bodner et al 2012;Hooshiar Kashani et al 2012;Perego et al 2012). Regional patterns have been characterized in tandem with reconstructing the emerging complexity of movements from Beringia/Siberia into the American continent.…”