Geneticists discover domestic cow genes in wild bison

(ORDO NEWS) — American scientists have found that all modern bison carry in their genome small but clearly identifiable sections of DNA inherited from cattle.

Apparently, bison and domestic cows have interbred with each other several times over the past two hundred years, which was the result of a sharp decline in the bison population at the beginning of the 19th century.

The idea that crosses with domestic cows could pose a threat to the genetic heritage of bison was first raised in 1995, and since then, the situation, unfortunately, has not improved.

A recently published article in Scientific Reports convincingly proved that all the main genomic lines of modern bison are not purebred, and all bison that exist today are hybrids of the original species and various breeds of livestock.

A team of researchers from the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University compared the genome sequences of major historical bison lines (nineteen modern and six museum lines) with 1,842 genomes of domestic cows.

In all analyzed bison genomes, scientists found traces of hybridization, that is, at least one of the ancestors of this bison did not belong to this species.

The findings refute the results of the same scientists, obtained 20 years ago, in which they spoke about several genetically pure herds: now, with more modern genetic technologies at their disposal, the same researchers have shown that even “pure” herds carry traces of hybridization.

Geneticists discover domestic cow genes in wild bison
A map showing the populations from which the genetic samples were taken. Round marks indicate modern bison populations, triangular marks indicate historical ones, whose material is represented by museum specimens. Green marks indicate populations of steppe bison, blue marks indicate forest bison, red marks indicate mixed populations. The dotted line indicates the historical range of the bison

Unfortunately, it is unlikely that bison could have escaped “genetic pollution”: their mass extermination in the United States almost brought these animals to the brink of extinction – when uncontrolled hunting, the reduction of available pastures and epidemics of infectious diseases reduced the number of bison from several million to several hundred.

As a result, the only surviving representatives of the species in North America were semi-domestic bison from private ranches, whose owners used wild animals to improve the quality of livestock.

As a result, in the 1870s, when the program to revive the American bison began, conservationists had to deal exclusively with hybrids.

The data obtained, although they speak of a supposedly irreversible loss of the bison’s genetic identity, nevertheless open up new opportunities for the conservation of existing animals.

Since the main problem of modern bison herds is low genetic diversity , the lack of “purebred” bison populations may allow their freer interbreeding and possibly controlled hybridization with livestock.

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