Researchers have engineered a courtship ritual from one species of fruit fly into another using genetic modification.\u00a0<\/p>\n
A Japanese research team tweaked a single gene in the fly Drosophila melanogaster, causing it to display a courtship ritual only previously seen in Drosophila subobscura.\u00a0<\/p>\n
The research shows that manipulations of relatively small chunks of genetic code can alter complex behaviors.\u00a0<\/p>\n
Dating as a fly is a complicated game. In the majority of fly species, D. melanogaster\u00a0included, male flies vibrate their wings, composing elaborate courtship \u201csongs\u201d to seduce their mates.\u00a0<\/p>\n
But D. subobscura have clearly decided the route to the heart is through the stomach. Males regurgitate food and offer their vomit to potential hookups as a loving gift. \u00a0<\/p>\n
D. melanogaster and D. subobscura\u00a0are relatively closely related species, but they still diverged from each other around 30-35 million years ago. In that time, a curious difference has emerged between the two species\u2019 brains.\u00a0<\/p>\n
In vomit-donating flies, the brain\u2019s courtship center has become linked to the neurons that produce insulin. In the ballad-penning D. melanogaster, these two brain areas aren\u2019t connected.\u00a0<\/p>\n
The researchers discovered this change by probing D. subobscura\u2019s genome. They added in short chunks of DNA that prevented specific genes in certain cells of the flies\u2019 brains from activating unless they were heated up.\u00a0<\/p>\n
They monitored the flies\u2019 courtship moves and saw that their charming regurgitation behavior only appeared when they turned on a group of just over a dozen insulin-releasing neurons in the flies\u2019 neurosecretory center, the pars intercerebralis.\u00a0<\/p>\n
In both species, a single gene, called \u201cFruitlessM\u201d or \u201cFruM\u201d, governs male courtship. They found that in D. subobscura, the small group of insulin-producing cells also made the FruM courtship protein and wired into courtship brain circuits. This wasn\u2019t the case in D. melanogaster.<\/p>\n
The team then used gene modification to activate the FruM gene in D. melanogaster\u2019s insulin-producing neurons. \u201cThe cells grew long neural projections and connected to the courtship center in the brain, creating new brain circuits that produce gift-giving behavior in D. melanogaster for the first time,\u201d said Ryoya Tanaka<\/a>, neurobiologist at Nagoya University and co-author of the new study in a press release<\/a>.\u00a0<\/p>\n Tanaka has studied Drosophila\u00a0mating for nearly a decade, previously mapping both species\u2019 courting behaviors and how fru influences them in a 2017 paper<\/a>.\u00a0<\/p>\n In contrast, turning off this small gene group in D. subobscura\u00a0stopped them from regurgitating.<\/p>\n