DNA analyses for other domesticated species (e.g., cattle, sheep, and goat) revealed that modern livestock has derived from a limited number of animals that were domesticated in just a few places 8-10 kya (2, 15, 26, 27). This finding is also substantiated by today's reduced genetic variation in these animals compared with their ancient forebears. For instance, mtDNA of modern taurine cattle falls into a few distinct haplogroups, suggesting that (almost) only the offspring of original livestock were used to establish herds elsewhere (14, 28). However, horse mtDNA tells a different story. Modern horse mitochondrial genomes, when analyzed at the highest level of molecular resolution, show a high diversity in terms of haplogroups. Moreover, most of the 17 haplogroups identified in domestic breeds are spread over different geographic areas. This finding should, however, be compared with the genetic traces of the male lines of modern horses: according to a recent study (29), there is virtually no sequence diversity in the male-inherited Y chromosome. This finding implies that the domestication of wild horses was a process that involved only closely related male horses but allowed for more variation in the female lineages.
Domestication of Wild Mares.
DNA analyses for other domesticated species (e.g., cattle, sheep, and goat) revealed that modern livestock has derived from a limited number of animals that were domesticated in just a few places 8-10 kya (2, 15, 26, 27). This finding is also substantiated by today's reduced genetic variation in these animals compared with their ancient forebears. For instance, mtDNA of modern taurine cattle falls into a few distinct haplogroups, suggesting that (almost) only the offspring of original livestock were used to establish herds elsewhere (14, 28). However, horse mtDNA tells a different story. Modern horse mitochondrial genomes, when analyzed at the highest level of molecular resolution, show a high diversity in terms of haplogroups. Moreover, most of the 17 haplogroups identified in domestic breeds are spread over different geographic areas. This finding should, however, be compared with the genetic traces of the male lines of modern horses: according to a recent study (29), there is virtually no sequence diversity in the male-inherited Y chromosome. This finding implies that the domestication of wild horses was a process that involved only closely related male horses but allowed for more variation in the female lineages.
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