The where and when of horses: Tracing horse domestication with mitochondrial haplogroups

Описание: Mitochondrial genomes from modern horses reveal the major haplogroups that underwent domestication. Achilli A, Olivieri A, Soares P, Lancioni H, Hooshiar Kashani B, Perego UA, Nergadze SG, Carossa V, Santagostino M, Capomaccio S, Felicetti M, Al-Achkar W, Penedo MC, Verini-Supplizi A, Houshmand M, Woodward SR, Semino O, Silvestrelli M, Giulotto E, Pereira L, Bandelt HJ, Torroni A. Proc Natl Acad Sci U S A. 2012 Feb 14;109(7):2449-54. doi: 10.1073/pnas.1111637109.

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The domesticated horse (Equus ferus) has been a major contributor to human development throughout history and across cultures. But exactly when and where did horses become domesticated? The answer isn’t as clear-cut as you’d think.

In 2012, scientist Alessandro Achilli and colleagues set out to expand our understanding of how horses came to be domesticated by conducting a phylogenetic analysis using mitochondrial DNA; mitochondria possess their own genome, and unlike the nuclear genome, which is contributed to by both parents, in animals mitochondrial DNA is inherited from the mother with very little parental recombination. By performing an ananlysis of 83 horse mitochondrial genomes collected from across Asia, Europe, and the Middle East, key information about the domestication of this species was revealed. Since mitochondrial DNA isn’t being recombined between two parents, almost all genetic variation occurs through spontaneous substitution mutations, which are simpler than genetic recombination to track. And by sequencing the complete mitochondrial genome, this investigation enabled the process of domestication at high genetic resolution.

Achilli ended up identifying 667 sites of mutation across all 83 genomes, or “haplotypes”. These
83 haplotypes were sorted into 18 major haplogroups, many of which had not been identified by previous studies. Achilli and colleagues identified haplogroups with frequency peaks among populations in Asia, with declining frequency in the Middle East, and then to Europe, inferring that these lines came from Asia. Using a molecular clock it was estimated that the most recent common ancestor of domesticated horse lineages was 140,000 years ago. This picture of how horses developed over time implicitly paints a picture of human history alongside them.

Creator: Declan White

References:
Achilli A, Olivieri A, Soares P, Lancioni H, Hooshiar Kashani B, Perego UA, Nergadze SG, Carossa V, Santagostino M, Capomaccio S, Felicetti M, Al-Achkar W, Penedo MC, Verini-Supplizi A, Houshmand M, Woodward SR, Semino O, Silvestrelli M, Giulotto E, Pereira L, Bandelt HJ, Torroni A. Mitochondrial genomes from modern horses reveal the major haplogroups that underwent domestication. Proc Natl Acad Sci U S A. 2012;109(7):2449-2454.
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