Sex or Sleep? Male Fruit Flies Make a Choice: Study

The University of San Diego’s Divya Sitaraman, assistant professor of psychological sciences, recently studied two fundamental behaviors in fruit flies: sex and sleep

When given a choice of sex or sleep, male fruit flies tend to opt for the latter, while female fruit flies think differently, according to research out of the University of San Diego.

Divya Sitaraman, an assistant professor of psychological sciences at USD, studied two fundamental behaviors needed to survive in fruit flies: sex and sleep. The research, conducted across both genders of fruit flies, aimed to learn how organisms prioritize behaviors when a choice must be made.

While some actions can be performed at the same time – like walking and drinking coffee – some behaviors cannot be performed simultaneously because they use shared resources. The nervous system has evolved ways of helping us focus on a task at hand. For instance, when we’re hungry, we choose to seek food before anything else.

Sitaraman’s research looks into the genetic, neuronal and precise circuit mechanisms that help organisms – in this case, fruit flies – make choices in social behavior.

It turns out, male fruit flies would rather sleep than have sex.

"They would always choose sleep over courtship," Sitaraman explained. "The females do not show the same preference for sleep over sex."

According to the study, male fruit flies prioritized behaviors differently than females in this scenario: when they were sleep deprived, they reduced their courtship behaviors.

Female fruit flies, however, did not.

“Genes important in sex determination also seem to play a critical role in these behaviors. The interplay between sex and sleep circuitry at the neuronal level seems sex-specific and functions very differently in female flies. Taken together, the study uncovered the role of genes in regulating sex-specific behaviors, interaction between circuits involved in different behaviors and sexual dimorphism in decision making,” a press release from USD stated.

Sitaraman said her study shows that decision-making and behavioral execution of those decisions “cannot be generalized in males and females.”

She said it’s important to study both male and female organisms to better understand behavior.

“We might be missing out a lot of the neuroscience of the sexual dimorphism of decision-making,” she added.

Sitaraman’s study was conducted in collaboration with scientists at Yale University, Howard Hughes Medical Institute and Southeast University in China; the discoveries were published in last month’s issue of Nature Communications, a journal that publishes high-quality research in biology, physics, chemistry, Earth sciences and related fields.

She said the study has been "a neuroscientist’s dream."

USD said the professor was awarded a grant from the National Institutes of Health (NIH) for $366,409 to study sleep regulation by dopamine.

That upcoming research, according to the university, may one day help scientists figure out ways to treat sleep disorders in humans.

“These studies will not only expose undergraduates to cutting-edge neuroscience research but also further the long-term goal of exploiting the experimental tractability of the fly as a model for mammalian sleep and reveal new hypotheses and approaches in understanding and treating clinically significant problems of sleep disorders,” a press release stated.

You can read the full study here.

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