DNA from domesticated chickens is tainting genomes of wild red junglefowl
Estimates suggest the wild birds have inherited 20% to 50% of their genomes from chickens
Peer-Reviewed PublicationIMAGE: RED JUNGLEFOWL ARE THE WILD ANCESTORS OF THE CHICKEN, AND THE TWO ARE KNOWN TO READILY ADMIX. IN THEIR STUDY, WU ET AL. FOUND EVIDENCE OF A LOSS IN WILD GENOTYPE IN THE RED JUNGLEFOWL ACROSS THE ANTHROPOCENE BY COMPARING CONTEMPORARY GENOMES WITH HISTORIC ONES FROM APPROXIMATELY A CENTURY AGO. IN THEIR NATIVE RANGE IN SOUTHEAST ASIA, FREE-ROAMING RED JUNGLEFOWL EXHIBIT DOMESTIC TRAITS INDICATIVE OF DOMESTIC INTROGRESSION INTO THE WILD POPULATION (SHOWN HERE). [PHOTO COURTESY OF YONG CHEE KEITA SIN] view more
CREDIT: WU ET AL, 2023. CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)
The red junglefowl – the wild ancestor of the chicken – is losing its genetic diversity by interbreeding with domesticated birds, according to a new study led by Frank Rheindt of the National University of Singapore published January 19 in the journal 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 acquire more DNA from chickens, they can lose their genetic diversity, potentially making them less resilient to changes in their environment.
In the new study, researchers contrasted whole genomes from 51 chickens and 63 junglefowl from across the wild bird’s natural range, to find signs of interbreeding. They saw that DNA from domesticated chickens is moving into wild junglefowl, and the scale of that movement has increased over recent decades. By comparing modern wild genomes to genomes of red junglefowl from approximately a century ago, the researchers estimate that the wild birds have inherited 20% to 50% of their genomes from domestic birds, depending on their location. The study also identified eight genes that differed greatly between domestic chickens and their wild ancestors, and which were likely key to developing the chicken as a livestock animal. These genes are involved in development, reproduction and vision.
The results of the study bring to light the ongoing loss of genetic diversity in the wild junglefowl, and the researchers suggest that efforts may be needed to protect its genome. Additionally, wild populations have value for 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. Losing that genetic diversity in red junglefowl may hinder scientists’ ability to safeguard one of humanity’s most important food sources.
The authors add: “Genomes of 100 year old birds show that modern wild junglefowl carry on average more domestic DNA than they used to. The wild genotype is an important reservoir of chickens’ genetic diversity and preserving it is critical.”
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In your coverage, please use this URL to provide access to the freely available article in PLOS Genetics:
http://journals.plos.org/plosgenetics/article?id=10.1371/journal. pgen.1010522
Press-only preview: https://plos.io/3WXmZNs
Contact: Frank Rheindt, dbsfre@nus.edu.sg
Image Caption: Red junglefowl are the wild ancestors of the chicken, and the two are known to readily admix. In their study, Wu et al. found evidence of a loss in wild genotype in the red junglefowl across the Anthropocene by comparing contemporary genomes with historic ones from approximately a century ago. In their native range in Southeast Asia, free-roaming red junglefowl exhibit domestic traits indicative of domestic introgression into the wild population (shown here). [Photo Courtesy of Yong Chee Keita Sin]
Image Credit: Wu et al, 2023. CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)
Image URL: https://plos.io/3W05Ph4
Citation: Wu MY, Forcina G, Low GW, Sadanandan KR, Gwee CY, van Grouw H, et al. (2023) Historic samples reveal loss of wild genotype through domestic chicken introgression during the Anthropocene. PLoS Genet 19(1): e1010551. https://doi.org/10.1371/journal.pgen.1010551
Author Countries: Australia, China, Germany, Singapore, Spain, UK, USA
Funding: MYW, GWJL, CYG were supported by the Singapore Ministry of Education under their MOE Tier 2 grant (A-0004777-00-00) awarded to FER. GF was supported by the Erasmus Mundus project EURASIACAT (ref. nr. 552067) coordinated by the University of Málaga. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
JOURNAL
PLoS Genetics
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Historic samples reveal loss of wild genotype through domestic chicken introgression during the Anthropocene
Parasitic mites’ biting rate may drive transmission of Deformed wing virus in honey bees
Study suggests small numbers of mites can infect many honey bees
Peer-Reviewed PublicationIMAGE: A YOUNG BEE EMERGES WITH DEFORMED WINGS CAUSED BY THE FEEDING OF AN INFECTIOUS MITE. MUCH FOCUS HAS BEEN ON THESE SYMPTOMATIC BEES. HOWEVER, MITES REGULARLY MOVE FROM ONE ADULT BEE TO ANOTHER TO FEED, LEAVING BEHIND A POPULATION OF SYMPTOMATIC BEES WHICH CAN STILL DEVELOP HIGH LEVELS OF VIRUS. view more
CREDIT: LAMAS, ET AL, 2023. (CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)
Varroa destructor is an ectoparasitic mite that can cause European honey bee colonies to collapse by spreading Deformed wing virus as they feed. A study published in PLOS Pathogens by Zachary Lamas and colleagues at the USDA-ARS and the University of Maryland suggests a relatively small number of mites can contribute to a large number of infected bees.
Arthropod disease vectors transmit pathogens while feeding on susceptible hosts. However, little is known about how the feeding dynamics of Varroa spread viruses in adult honey bees. In order to better understand Varroa mite parasitism on honey bees, researchers conducted a series of experiments. First, they used fluorescent microspheres to test if Varroa were feeding on adult bees each time they entered a known feeding position. They next determined whether microspheres could be transferred from a Varroa to an adult bee via Varroa feeding by allowing Varroa to feed on bee pupae which had been injected with fluorescent microspheres. In the third experiment, researchers observed mites switching from adult bee host to host. The researchers then observed how a single mite could spread pathogens by feeding on multiple bees and calculated the relative risk of Varroa parasitism on adult workers.
Mites with high virus levels and which switched the most frequently contributed to the highest mortality in adult honey bees. Varroa are promiscuous feeders and switch hosts at a high rate. Mites switching hosts at the highest frequency were responsible for nearly three times as many parasitized hosts as their lower switching counterparts. Future studies are needed to better understand the mechanisms driving mites to switch hosts.
According to the authors, “Our work shows that viral spread is driven by Varroa actively switching from one adult bee to another as they feed. Relatively few of the most active Varroa parasitize the majority of bees. The ability to parasitize and infect multiple adult bees provides the best explanation to date for the maintenance and subsequent host-to-host spread of viruses among the long-lived worker bees common in these crowded and vulnerable colony populations”.
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In your coverage, please use this URL to provide access to the freely available article in PLOS Pathogens: http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1011061
Citation: Lamas ZS, Solmaz S, Ryabov EV, Mowery J, Heermann M, Sonenshine D, et al. (2023) Promiscuous feeding on multiple adult honey bee hosts amplifies the vectorial capacity of Varroa destructor. PLoS Pathog 19(1): e1011061. https://doi.org/10.1371/journal.ppat.1011061
Author Countries: Turkey, USA
Funding: ZSL was funded by the PAm-Costco Fellowship. https://www.projectapism.org/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
JOURNAL
PLoS Genetics
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Promiscuous feeding on multiple adult honey bee hosts amplifies the vectorial capacity of Varroa destructor
ARTICLE PUBLICATION DATE
19-Jan-2023
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