Genetic Composition of Social Environment Influences Behavior Among Zebrafish

A new study suggests that interactions of animals of the same species shape many of its biological aspects, and that includes their social behavior.

These social genetic effects happen when the defined set of observable traits of an individual, called the phenotype, is affected by the genetic features from the same species. It is common in many animals and implies consequences for their health state or evolutionary history.

Investigating How the Social Environment and Oxytocin Regulates Social Behavior

An international team of researchers led by Rui Oliveira studied how oxytocin and social environment influence the social behavior of zebrafish. Oxytocin is an important molecule responsible for the regulation of social behavior.

They used zebrafish (Danio rerio) as their model organism as they try to understand how social genetic effects influenced the interaction between the social environment, in this case, the shoal, and the focal individual.

The researchers divided the zebrafish into two groups in which one group is the same zebrafish found in nature, and the other group is the experimental group wherein they removed the oxytocin gene, which makes the animal unable to function.

The zebrafish is placed in the presence of the shoal, which acts as the social environment and is genetically similar to them or not. Then, they assessed the individuals in their social preference or their motivation in approaching the same shoal, also their social recognition or the ability of the individual to distinguish between different shoals, and lastly, the social integration and influence, which quantify how well the individual can integrate itself in the shoal and how much the social environment influences its behavior.

The results of the study showed that depending on whether the shoal has oxytocin or not, the social preference and social integration and influence change.

On the other hand, the genetic features of the individual determine its ability to create memories, which means that they could distinguish between different shoals.

Rui Oliveira explains that "the genetic differences of the social group interact with the ones of the individual during the acquisition of social behaviors and development, and in some cases, they can revert behavioral characteristics associated with oxytocin."

Role of Oxytocin in Regulating Behavior

The hypothalamus produces the oxytocin, which is then secreted by the pituitary gland. This hormone plays a vital role in childbirth and also helps in male reproduction.

It is sometimes called the "cuddle hormone" because it is released when people snuggle of bond socially. According to a study in 2009 published in Hormones and Behavior, the pituitary gland releases oxytocin even when someone plays with their dog.

Moreover, this hormone also intensifies memories of bonding that have gone bad, like in cases where men have poor relationships with their mother, and it can make people less accepting of people that they think like outsiders. In short, oxytocin makes the individual feeling cuddly or suspicious of other people depending on the type of environment.

Understanding the role of oxytocin will help people take better care of themselves and lead them to a better understanding of their bodily functions.