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Many animal species form social groups and behave collectively: A herd of elephants follows their matriarch, birds in flocks fly together, people gather at concert events. Researchers found that even common fruit flies organize themselves into regularly spaced clusters.
In these social networks, certain individuals will often stand out as “gatekeepers” and play an important role for cohesion and communication within the group.
And now scientists believe there is evidence of how central you are in your social network; This concept, which they call “high betweenness centrality”, may have a genetic basis. New research published Tuesday in the journal Nature Communications has identified a gene responsible for regulating the structure of social networks in fruit flies.
The study’s authors named the gene in question “degrees of Kevin Bacon,” or dokb, after a game that required players to link celebrities to actor Bacon through their shared movies in as few steps as possible.
Inspired by “six degrees of separation,” the theory that no one in the world is more than six relationships away from other people, the game became a viral phenomenon three decades ago.
The actor is a good example of a person with “high betweenness centrality,” said senior author Joel Levine, a professor of biology at the University of Toronto who went to high school with Bacon in Philadelphia.
Aware of Levine’s connection to Bacon, the study’s lead author, Rebecca Rooke, a postdoctoral biology researcher at the University of Toronto Mississauga, suggested the name for the gene.
“Degrees of separation are a real-world thing for us,” Levine said.
Levine explained that having a high level of centrality in a group network can be positive or negative.
“Sharing and communication patterns can be absolutely amazing,” he said. “You also have patterns that contribute to the spread of deadly diseases and infectious diseases, but the structure of the group is the same structure. “It’s not good or bad, positive or negative.”
Levine said the “Kevin Bacon degrees” gene is specific to the central nervous systems of fruit flies, but he thinks similar genetic pathways may be found in other animals, including humans. The work opened new opportunities to explore the molecular evolution of social networks and collective behavior in other animals.
The gene behind fruit fly social networks
The researchers investigated a number of gene candidates in fruit flies, a common laboratory organism used in genetic studies.
“We found two versions of the dokb gene, and one version produces networks with high betweenness centrality and the other version produces networks with low betweenness centrality,” Levine said.
“A network with high average centrality indicates that there are individuals in the network who are important for the flow of information from one part of the network to other parts.”
The team used gene editing techniques to knock out and replace these different variants to see what happened between different fly species. This change affected interaction patterns among a network of flies, and a social group adopted the pattern of the donor variant.
“The difference we’ll see is a difference in group cohesion. It’s not a difference you can see with the naked eye,” Levine said.
If you observe video footage of fruit flies on a plate in the lab, Levine said, they interact with each other and create repeatable patterns specific to different species that can be analyzed statistically.
“What we know is that the groups they’re in have a repeatable structure,” Levine said. “And we imagine that these structures make it easier for them to live.”
In nature, fruit flies exhibit group behavior when laying eggs and when encountering predators, Levine said.
“We do not characterize in our paper what actually flows in the network, so it is difficult to predict what advantages/disadvantages there are for flies forming these different interaction patterns,” he explained in an email.
“However, we showed that two different dokb variants are present in many wild fly species worldwide and that one of these variants is associated with low-elevation environments,” Levine said. “Maybe certain interaction patterns are advantageous at lower altitudes? Again, we’re not testing this directly, so this is just speculation.”
Allen J. Moore, a distinguished research professor in the University of Georgia’s department of entomology, said in an email that the research was a “careful study” and agreed with the findings.
“Although it’s a first step — and we (and they) don’t know exactly how this works — it’s fascinating to find a single gene that affects social adaptation,” said Moore, who was not involved in the research but reviewed the paper. before publication.
What do fruit flies and humans have in common?
Known for hanging around fruit bowls, Drosophila melanogaster has been a model organism in the study of genetics for over 100 years. Insects breed quickly and are easy to care for.
Although flies are very different from humans, these creatures have long been at the center of biological and genetic discoveries.
“Fruit flies are useful because of their manipulation power. We can experimentally investigate things in Drosophila that we can only study indirectly in most organisms,” Moore said.
The tiny creatures share about 60% of our genes, including those responsible for Alzheimer’s, Parkinson’s, cancer and heart disease. Research involving fruit flies has previously shed light on mechanisms of inheritance, circadian rhythms and mutation-inducing X-rays.
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