Could domestication be linked to animals’ gut bacteria?

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Researchers look at the guts of chicken ancestors to gain insight into domestication.

Image credit: Thomas Iversen on Unsplash

Say “pet” to anyone and the idea that comes to their mind will likely differ depending on the culture and society. Do I mean pet or livestock? Personal security guard or personal assistant? A means of transport or a baggage carrier? It depends on when you ask this question as well. Images of domestic cats were ubiquitous in ancient Egyptian culture, imbued with religious and mystical meanings. Cats are ubiquitous in modern media too, although it seems mostly for the simple reason that we find these animals funny.

Regardless of their meaning and significance, all domestic animals share the common feature that they differ from their wild ancestors in that they have such an interdependent relationship with humans that they, and other successive generations, have become completely different species. The dog is not a wolf, nor is the cat a lion. Try jumping on the back of an uninvited zebra and you will likely get to the hospital.

Wild animals do not have the same relationships with humans as domestic animals, the evolution of which directly shaped man nearly 15,000 years ago.

But while the visual and behavioral differences between wild and domestic animals are the clearest expression of genetic differences, the least obvious but most surprising change may be the first to occur in the species’ early domestication: gut bacteria.

A team of researchers led by Lara Poetz and Thomas Gilbert at the Center for Evolutionary Hologenomics at the GLOBE Institute at the University of Copenhagen hypothesized that gut microbes may cause one of the oldest phenotypes—observable characteristics, including behavior, regulated by genes—to change with the domestication of wild animals. and experiments to support it.

Posted in advanced geneticsThe team compared the gut microbiome of two lines of red bushbird – the ancestors of domestic chickens – that were raised solely due to either high or low fear of humans over eight generations. The link between fear and the gut microbiome has only recently been investigated, and since the main characteristic of pets is their lack of fear of humans compared to their wild counterparts, Puetz and her colleagues wanted to see – in terms of their gut microbiome – exactly how this change occurs from early on from feeling fear to Feeling safe in the presence of people.

Using a technique called genome-resolved metagenomics, the team found a marked difference in the neuroactive metabolites associated with fear conditioning between the two groups of birds.

Two groups were the main bacteria of interest octopacil And Clostridialisand found that the group of low fear junglefowl had low levels of the former and high levels of the latter in gut bacteria. the last one, Clostridialis, was previously associated with reduced stress in Japanese quail, and it is thought that this family of bacteria could be responsible for enhancing the biosynthesis of serotonin, which was found at higher levels in males of low-fear red bushbird.

With domestication comes control, and the great control imposed on a pet is its diet. So it is perhaps easy to think that domesticated jungle birds ate differently than their wild counterparts, and thus the change in gut bacteria is a product of diet. However, in this study, the two groups of bush chickens were raised in identical environments, including what they ate. The authors therefore rule out change in diet as a driver of changes in the gut microbiome.

However, the authors stress that their findings do not suggest a specific causative role for gut bacteria in fear during domestication, but rather suggest that their findings could be a starting point for further studies. After ruling out dietary changes as a driver of differences in low and high fear groups, they also recognized that host genes also play a role in the composition of the gut microbiome.

They therefore concluded that the phenotype selected in the red junglefowl could reflect a convergence of various factors including microbes, as well as the host and its environment.

Reference: Lara C. Puetz et al. Gut microbiota associated with reduced fear of humans in the red bushbird has implications for early domestication, Advanced Genetics (2021) DOI: 10.1002/ggn2.202100018

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