Hen DNA is changing the genes of its progenitor jungle fowl

Today’s red jungle fowl — the wild ancestor of the domesticated chicken — is becoming more and more chicken-like. New research shows that most of the DNA in wild birds was inherited from chickens, and only recently.

Ongoing hybridization between two birds could threaten the future of wild jungle fowl populations, Even hampering humanity’s ability to breed better chickensthe researchers reported on January 19 at PLOS Genetics.

Red Jungle Chicken (jungle chicken) are forest birds native to parts of Southeast and South Asia. Thousands of years ago, humans domesticated poultry, paddy fields possibly in the area (serial number: 22/6/6).

“The chicken is arguably the most important domestic animal on Earth,” says evolutionary biologist Frank Rheindt of the National University of Singapore. He points to their ubiquity and abundance across the globe. Chicken is also one of the cheapest sources of animal protein that humans have.

Domestic Chicken (Chicken) known to interbreed with jungle fowl near human settlements in Southeast Asia. Given the unknown effects on jungle fowl and the importance of chickens to humans, Rheindt and his team wanted to gather more details. Wild jungle chickens contain rich genetic diversity and can serve as an important resource for breeding chickens resistant to disease or other threats.

The researchers analyzed and compared the genomes — the organism’s complete complement of DNA — of 63 jungle fowl and 51 chickens from across Southeast Asia. Some of the jungle fowl samples came from museum specimens collected between 1874 and 1939, giving the team an idea of ​​how the genetic makeup of the jungle fowl has changed over time.

Over the last century or so, the wild jungle fowl genome has become increasingly similar to that of chickens. The team found that about 20 to 50 percent of the modern jungle fowl genome originated from chickens. In contrast, many jungle fowl that are about 100 years old have chicken blood shares in the range of a few percent.

Rheindt said the rapid change likely came from the expansion of human communities into the region’s wilderness. Most modern jungle fowl live near human free-range chickens, with which they often interbreed.

Rheindt said such hybrids have become “now almost the norm” of any globally domesticated species, such as dog-wolf hybrids and domestic cat hybrids with wildcats. At the same time, the pigs are working with wild boar and ferrets There are skunks.

Claudio Quilodrán, a conservation geneticist at the University of Geneva who was not involved in the study, says wild populations that interbreed with their domesticated counterparts can acquire physical or behavioral traits that alter how the hybrids function in their ecosystems.

The impact is likely to be negative, Quilodrán said, because some traits in wild populations were honed for human use, not for survival in the local environment.

Wild jungle chickens have also lost genetic diversity through interbreeding. The heterozygosity of birds — a measure of a population’s genetic diversity — is now only a tenth of what it was a century ago.

“This result was initially counterintuitive,” Rheindt said. “If you mix one population with another, you generally expect higher genetic diversity.”

But the genetic diversity of domestic chickens is so low that certain versions of the jungle fowl gene are being swept out of the population by a tsunami of genetic homogeneity. A reduction in the genetic toolkit of these animals could leave them vulnerable to conservation threats.

“Having a lot of genetic diversity in a species increases the chances that certain individuals contain genetic backgrounds that adapt to a variety of different environmental changes and diseases,” says computational biologist Graham Ethering of the Earlham Institute in Norwich, UK. Dun said he was not involved in the study.

A shallower jungle fowl gene pool could also mean fewer resources for breeding better chickens. Genetics from wild relatives are sometimes used to enhance resistance to pests and diseases in domesticated crops. For this reason, the jungle fowl genome may be of similar value.

“If this trend continues, future human generations may only have access to the chicken’s full ancestral genetic diversity in museum specimens,” Rheindt said, which could hamper chicken breeding efforts using wildfowl genes.

Some countries, such as Singapore, have begun managing jungle fowl populations to reduce interbreeding with chickens, Rheindt said.