Scientists study how animals spend winter, finding fruit flies restructure body clocks into separate seasonal patterns
Scientists studying how animals spend the winter have found that fruit flies completely rebuild their internal clocks to switch to a separate seasonal pattern. For context, fruit flies are tiny insects that feed on ripe, rotten, or fermented fruits and vegetables. They are usually about 2-4 mm long, with a tan or yellow-brown body, red eyes, and transparent wings.There are two common ways people use this term: Household fruit flies and laboratory fruit fliesThe discovery reveals a genetic winter lock that keeps insects in a low-activity state until warm weather returns. The study, led by researchers at Washington State University, found that the body clock doesn’t just run slower in cold weather. Instead, it changes its molecular structure to run an entirely different seasonal program.The findings, published in the journal Science Advances, could lead to new ways to target agricultural pests and help researchers understand why certain human health conditions change with the seasons.
Splicing internal clock
To understand seasonal changes, the team focused on a core gene within the circadian clock called “timeless,” which regulates daily biological rhythms.As winter approaches, genes undergo a process called alternative splicing. This mechanism allows individual genes to arrange their code in different ways and produce completely different proteins based on environmental cues. A winter-specific version of the protein reshapes the fly’s daily activity patterns and completely shuts down its reproductive system, effectively keeping the insect dormant.Sergio Hidalgo, lead author of the study and an assistant professor at the Washington State University College of Veterinary Medicine, explained that the discovery solves a long-standing mystery about how animals handle seasonal changes.“We have long known that animals use environmental cues to prepare for seasonal changes, but we have not yet understood exactly how the circadian clock integrates this information,” Hidalgo said. “We found that the clock itself can be reset to a winter state, helping the animals stay there until conditions are favorable enough to switch back to summer mode.”For decades, scientific models of the circadian clock were based almost entirely on how organisms functioned during the warmer months. This new evidence shows that organisms are not restricted to a single, strict internal clock that runs the same way year-round.“We’ve been working on what is essentially a summer version of the clock for years,” Hidalgo said. “This work shows that the clock can be modified during the winter, creating a functionally different system that helps animals maintain their winter schedule.”
Professor Sergio Hidalgo (left) works in the lab with intern Audrey Berry (Photo credit: College of Veterinary Medicine/Ted S. Warren)
survival blueprint
Adapting to seasonal changes is a basic survival requirement in nature. Microorganisms, complex plants, and large animals all rely on external triggers, such as temperature changes and shorter day lengths, to predict the onset of winter.These environmental changes prompted humans to adopt physical survival strategies, including long-distance migration, hibernation, moratorium on reproduction, and deep dormancy. While scientists understand what triggers these responses, the exact biological pathways that coordinate these systemic changes remain unclear.The discovery of winter locks suggests that the fly’s genetic machinery directly integrates these external signals to rebuild its internal clock. The fly will remain locked in this low-power state until environmental conditions improve significantly, providing a clear signal that it is safe to return to summer mode.The research project is a collaborative effort that combines genetic data and resources from Washington State University and the University of California, Davis. Co-authors include Audrey Berry, a University alumna and a research intern in Hidalgo’s lab.
Targeting pests and human rhythms
The discovery of this seasonal genetic switch opens up practical possibilities for managing destructive insects. Hidalgo suspects that the same or similar molecular mechanisms control the timing of seasons in major agricultural pests and disease-carrying insects such as mosquitoes.Most modern pest control strategies focus on direct, immediate eradication. Understanding winter locks could allow scientists to develop ways to disrupt the body clock itself. By interfering with the splicing of genes that allow insects to survive winter or drought periods, researchers may be able to wipe out pest populations before they become active in the spring.The study also provides new clues to researchers studying human biology. Many medical conditions, including seasonal affective disorder and various neurological and psychiatric disorders, follow different seasonal patterns. The exact biological processes that drive these changes in human health remain poorly understood.Drosophila and humans have very different biological systems, but the discovery that a core clock gene can radically reorganize itself across seasons gives medical researchers a concrete molecular starting point. Scientists can now study whether similar genetic changes occur in the human body clock during the darker months of the year.
