Flockmate or loner? Identifying the genes behind sociality in chickens

Sociality and social behaviour covers a wide range of behaviours. Dogs seeking human contact and honeybees using complex waggle dances to exchange information on where to find good food sources are two examples from the animal world. But what actually governs social behaviour?

"By identifying the genes responsible for the variation in such sociality we can understand how sociality is formed and how social behaviour is controlled at a genetic level. Why some people or animals are more gregarious by nature and others more independent is just one such example," says Dominic Wright, senior lecturer at the Department of Physics, Chemistry and Biology (IFM), who has led the study.

To assess this, the researchers used a cross between wild and domestic chickens. The AVIAN research group at Linköping University is one of the few groups in the world with a breeding population of Red Junglefowl, the wild ancestor of the domestic fowl. For 8,000 years, humans have selected the individuals that have desirable traits and bred them, a process known as domestication. As a result, today's domestic fowl and the original wild fowl differ strongly in their social behaviour. For example, Red Junglefowl typically take longer to approach other birds, but spend more time with them when they do. By crossing the domestic and the wild fowl for several generations, the researchers obtained chickens that exhibited a large range of social behaviour.

The researchers measured sociality by placing chickens in a novel environment (a large box) and observing how likely they were to seek contact with other chickens. A more social chicken approaches the others more rapidly and spends less time exploring the new surroundings. The same behaviour is also displayed by more anxious chickens. The investigators also measured gene expression in one of several regions in the brain involved in the regulation of social behaviour, the hypothalamus. By correlating behaviour, gene expression and genetic variants, the researchers identified five genes that seem to control aspects of this behaviour.

"Although these genes had been implicated with behaviour or nervous system function previously, this is the first time they have been shown to control sociality also. We also found that several of the genes affect both sociality and anxiety in the chickens," says Dominic Wright.