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Many species of animals form social groups and behave collectively: A herd of elephants follows their matriarch, birds fly together, people gather at concert events. Even humble fruit flies organize themselves into regularly spaced clusters, according to researchers.
Within these social networks, certain individuals often stand out as “leaders,” and will play an important role in integration and communication within that group.
And now, scientists believe there is evidence that a concept they call “high betweenness centrality” and how central you are to your social network 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 authors of the study named the gene in question “Kevin Bacon degrees,” or dokb, after a game that requires players to connect famous people to the actor Bacon as little as possible through the movies they have in common.
Inspired by “six degrees of separation,” the theory that no one is more than six relationships away from anyone else in the world, the game became a viral phenomenon three decades ago.
Senior author Joel Levine, a professor of biology at the University of Toronto who went to high school with Bacon in Philadelphia, said the actor is a good human example of “high faculty centrality.”
Aware of Levine’s connection to Bacon, study lead author Rebecca Rooke, a postdoctoral fellow in biology at the University of Toronto Mississauga, suggested the gene’s name.
“Separation steps is a very real thing for us,” Levine said.
High measures of centrality in a group network can be positive or negative, Levine explained.
“Patterns of sharing and communication can be 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. It’s not good or bad or positive or negative.”
Levine said the “Kevin Bacon steps” gene was specific to the central nervous system of fruit flies, but he thought similar genetic pathways would exist in other animals, including humans. The study opened up new opportunities to investigate the molecular evolution of social networks and collective behavior in other animals.
The gene behind fruit fly social networks
The researchers investigated several candidate genes in fruit flies, a common laboratory organism used to study genetics.
“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,” said Levine.
“A network with high mean centrality indicates that there are individuals in the network who are important to the flow of information from one part of the network to other parts.”
The team used gene editing techniques to knock out and swap these different versions to see what happened among different types of flies. This exchange influenced the patterns of interaction among a network of flies, with a social group adopting the pattern of the opposite donor.
“The difference we will see is a difference in group cohesion. It’s not a difference you can see with the naked eye,” said Levine.
If you watch video footage of fruit flies in a dish in the lab, Levine said they appear to be interacting with each other, creating repeatable species-specific patterns that can be analyzed statistically on them.
“We know that the groups they’re in have a repeatable structure,” Levine said. “And we imagine that those structures facilitate the way they live.”
In nature, fruit flies show group behavior when laying eggs and finding predators, Levine said.
“In our paper, we do not show what is flowing through the network, so it is difficult to speculate on the advantages/disadvantages of flies that create these different interaction patterns,” he explained in an email.
“However, we show that the two different dokb variants exist in several species of wild flies around the globe and that one of these variants is correlated with low-elevation environments,” Levine said. “Perhaps certain patterns of interaction are advantageous at low altitude? Again, we don’t test this directly, so it’s just speculation.”
Allen J. Moore, distinguished research professor at the University of Georgia’s entomology department, said in an email that the research was “careful work” and he agreed with the findings.
“Although it’s a first step – and we (and they) don’t know exactly how it works – it’s really interesting to find one gene that affects social cohesion,” said Moore, who was not involved in the research but reviewed the paper. before publication.
What fruits do flies and humans have in common
Drosophila melanogaster, known for hovering around bowls of fruit, has been a model organism for exploring genetics for over 100 years. The insects breed quickly and are easy to keep.
Although flies are very different from humans, the creatures have long been central to biological and genetic discovery.
“Fruit flies are useful because of the power of manipulation. We can investigate things experimentally in Drosophila that we can only examine indirectly in most organisms,” said Moore.
The little creatures share almost 60% of our genes, including those responsible for Alzheimer’s, Parkinson’s, cancer and heart disease. Research involving fruit flies has previously provided insight into the mechanisms of inheritance, circadian rhythms and mutation-causing X-rays.
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