All domestic chickens are derived from a single ancestor — one of the subspecies of wild bankivskogo cock that inhabits southwest China, Northern Thailand and Myanmar. To such conclusion the team of scientists analyzing the genomes of 863 wild and domestic chickens. As noted in an article for the journal Cell Research, the study refutes the popular hypothesis of independent domestication of chickens in several regions of Asia.
Chickens (Gallus Gallus domesticus) are among the most important farm animals. For millennia they regularly supply the people with meat, eggs and feather. Humanity, in turn, provided the chickens, the conditions for the explosive growth of the population: by some estimates, the world today is home to around 22 billion of these birds.
About the initial stages of these mutually beneficial relationships are little known. Scientists have no doubt that the ancestor of the domestic chicken were wild bankivski cock (G. gallus), which is common throughout Southeast Asia. However, the exact time and place of its domestication remain controversial.
A team of specialists, led by ya-Ping Zhang (Ya-Ping Zhang) from the Institute of Zoology in Kunming, I decided to shed some light on this question. To do this, scientists have carefully analyzed the complete nuclear genomes 863 chickens. Among them were representatives of various domestic breeds, as well as all five subspecies bankivskogo rooster and three wild species of the genus Gallus.
The study showed that the subspecies bankivskogo cock strongly enough differed from each other from a genetic point of view. In this case the closest relative of the domestic chicken turned out to be a subspecies G. g. spadiceus, inhabit southwest China, Northern Thailand and Myanmar. Most likely, in this region bankivskih cocks and domesticated. A comparison of genomes shows that this happened about nine and a half thousand years ago.
However, the contact of chickens with wild relatives has not stopped. From the hearth of domestication of birds began to spread across South-East Asia, where they mixed with local subspecies bankivskih cocks (G. g. bankiva, G. g. murghi and G. g. jabouillei). Traces of these relations is still widely represented in the genome of chickens, not only Asian species, but white leghorns. The contribution of other wild species for example, green (G. varius) roosters and Ceylon (G. lafayettii) is much less significant and is monitored only in some local breeds.
At the last stage, team members identified areas of the chicken genome, which upon domestication has undergone the greatest selective pressures. Among them were the genes responsible for the development of the nervous system, muscles and bones and genes-regulators of growth, metabolism and reproduction. Under the influence of artificial selection some of their options was fixed that made the chickens more tolerant of people, but also accelerated their sexual maturity and increased egg production.
According to the authors, the data obtained allow us to reconstruct the history of chickens is much more detailed than before. In addition, they contradict the popular hypothesis that these birds were domesticated independently in several regions of Asia.
In our days, the industrial breeding of chickens has become a high-tech agriculture. For example, recently scientists have created a system of automatic recognition alarm the chickens. The algorithm will warn the farmers about what Chicks feel uncomfortable.
Sergey Knee High