With a gene transferred, a behavior between different species

For 35 million years, they courted females with song, but modifying a single gene was enough for them to adopt the behavior of another species , offering gifts. The results of an experiment published in the journal Science and conducted in Japan are a world first . It demonstrates how modifying a single gene is enough to induce new connections between neurons and thus transfer behaviors typical of one species to another . The experiment was conducted on fruit flies by the Japanese National Institute of Information and Communications Technology (NICR) in collaboration with Nagoya University. "We have demonstrated how we can trace the genetic roots of complex behaviors such as nuptial gifting to understand how evolution creates entirely new strategies that help species survive and reproduce ," said Daisuke Yamamoto of the NICT, who coordinated the research with his colleague Yusuke Hara, also of the institute. By activating a single gene , researchers have been able to make a species of fruit fly ( Drosophila melanogaster ) perform a gift-giving ritual that individuals of that species had never performed before and which is instead typical of the species Drosophila subobscura . The two species diverged along the evolutionary scale 35 million years ago . Under normal conditions, male Drosophila melanogaster court females by rapidly vibrating their wings in order to obtain a sort of song , while male Drosophila subobscura court females by regurgitating food and offering it as a gift . The reason for this difference lies in a gene called 'fruitless' or 'fru' , common to the two species and known to control courtship behavior in males. In both species, the gene is present in neurons that control the production of insulin , the hormone that acts as a neurotransmitter in the brain. However , in flies that court with gifts , the insulin-producing neurons are connected to the courtship control center in the brain , while in flies that court with songs, they are not . Using embryos modified with heat-activated proteins, the researchers identified a cluster of about 18 insulin-producing neurons that control the male- specific protein FruM , which are clustered in a part of the brain called the pars intercerebralis . "When we activated the fru gene in insulin-producing neurons in flies that we court with songs to produce FruM proteins , the cells developed long neural projections and connected to the courtship center in the brain, creating new brain circuits that induced courtship with gifts ," says co-author Ryoya Tanaka of Nagoya University. This is the first time such a phenomenon has been observed. "Our findings," Hara said, "indicate that the evolution of new behaviors does not necessarily require the emergence of new neurons ; on the contrary, small-scale genetic reorganization in some pre-existing neurons can lead to behavioral diversification and ultimately contribute to species differentiation ."