Human Mitochondrial DNA from 5th – 3rd Millennia BCE: An Analysis of Iberian Populations
Well-documented demographic changes accompanied the onset of the Neolithic but subsequent population dynamics are less clear. Ancient DNA data from the Neolithic period of coastal regions of the Iberian Peninsula are relatively scarce. The aim of the present study was to sequence DNA from Neolithic Iberians from the Spanish Levant (Catalonia) and the Portuguese Estremadura, Algarve and Alentejo regions in an attempt to explore the population dynamics in these regions following the adoption of agricultural practices. Samples were collected from the Late Neolithic site ‘La Sagrera’ (N=13), situated in modern day Barcelona, and from four sites in Portugal; Castelo Belinho (Early Neolithic, N=8), Algar do Barrão (Middle Neolithic, N=3), and Casais da Mureta (N=3) and Anta da Cabeceira (N=1), both Late Neolithic. Mitochondrial DNA was extracted, amplified and sequenced. Haplogroup assignments were made using diagnostic SNPs. Databases of ancient and modern mitochondrial DNA were searched for haplotypes, and likelihood ratios were calculated to investigate kinship between individuals with shared haplotypes. Obtained sequences were grouped with previously published data and haplogroup frequencies were compared with other ancient populations, and genetic distances were calculated between ancient and modern Iberian populations. Sequencing was largely unsuccessful for the Portuguese sites due to sub-optimal sample preservation. Regionally, ancient DNA data is relatively scarce, suggesting local climate may promote DNA degradation. Haplotypes were obtained for 10 of the 13 individuals from La Sagrera. Matrilineal kinship was established for two individuals sharing a haplotype. However, it was not possible to ascribe a kinship based burial pattern at this site. FST analysis indicated a discontinuity between pre- and post-Neolithic populations, though haplogroup analysis indicated a Mesolithic ancestry throughout the Iberian Neolithic. Middle and Late Neolithic populations were genetically divergent from modern Iberian populations, indicating that processes subsequent to the Neolithic period may have influenced the modern mitochondrial gene pool in the region. Haplogroup analysis indicated an increase in haplogroup diversity coinciding with the onset of the Neolithic, and a subsequent reduction in diversity into the Middle and Late Neolithic periods.
GF Human ecology. Anthropogeography, QH301 Biology, QH426 Genetics
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