A new study led by Frank Reindt of the National University of Singapore published Jan. 19 in the journal Red Junglefowl — the wild ancestor of chickens — is losing its genetic diversity by interbreeding with domesticated birds. PLOS Genetics.
Humans domesticated the red junglefowl in tropical Asia somewhere between 3,000 and 10,000 years ago, but wild and domestic birds can still interbreed. This is a concern for red junglefowl conservation, because as wild populations gain more DNA from chickens, they can lose their genetic diversity, which can make them less resistant to changes in their environment.
In the new study, researchers compared the entire genomes of 51 chickens and 63 forest fowl across the wild birds’ natural range, to find signs of mating. They’ve seen DNA from domesticated chickens pass into wild jungle fowl, and the magnitude of that movement has increased over recent decades. By comparing modern wild genomes with those of red junglefowl from nearly a century ago, researchers estimate that wild birds have inherited 20% to 50% of their genomes from domestic birds, depending on their location. The study also identified eight genes that differ significantly between domesticated chickens and their wild ancestors, which were likely key to the development of chickens as a domestic animal. These genes are involved in development, reproduction, and vision.
The study results highlight the ongoing loss of genetic diversity in wild junglefowl, and the researchers suggest that efforts may be needed to protect its genome. In addition, wild populations are valuable to agriculture because they can serve as a reservoir of genetic diversity that researchers can tap into to improve domesticated species—for example, finding genetic variants that make an animal more resistant to a particular disease. The loss of this genetic diversity in the red jungle fowl could hamper scientists’ ability to protect one of humanity’s most important food sources.
The authors add: “The 100-year-old genomes of birds show that modern wild forest fowl carry on average more native DNA than they did before. The wild genotype is an important repository of chicken genetic diversity and its preservation is critical.”