Tokyo, Japan – Researchers at Tokyo Metropolitan University have studied how fruit flies tune their development in response to environmental changes (diapause). Studying fruit fly strains from different latitudes across Japan, they showed that the sensitivity to starting reproductive diapause varies smoothly with local conditions. Through genetic sequencing, they found that the timeless (tim) gene plays a key role, adding to growing evidence that diapause is strongly affected by genes regulating circadian rhythm.
Animals have a range of survival strategies to deal with changes in their environment. One of the most well-known is hibernation: some animals can slow down their metabolism to spend the winter months without food. In fact, some organisms not only slow down their energy needs, but delay their own development. This is called diapause, and is commonly observed in arthropods, especially insects.
Reproductive diapause, where organisms delay their reproductive development, has been a topic of intense interest in understanding how organisms adapt and survive in harsh environments. While the sensitivity of insects in whether they go into diapause is known to vary with conditions, the exact genetic mechanisms by which these strategies are passed on are not yet understood.
In groundbreaking work, a team led by Professor Aya Takahashi from Tokyo Metropolitan University studied reproductive diapause in fruit flies, seeing how their sensitivity to starting diapause changes with temperature and length of days. Their survey focused on the Drosophila triauraria species and covered a wide range of latitudes across the Japanese archipelago. Previous work had found that strains found in the north showed a strong sensitivity to length of days, while strains found in the south failed to arrest their reproduction despite short-day conditions.
Studying strains found over a range of latitudes, the team found that there was a smooth variation in sensitivity to diapause induction with both air temperature and the length of days in both males and females. Quantitative studies of diapause in insects, particularly those that include males, are very rare, and promise new comparisons between how males and females respond to harsh conditions. For example, they found suggestions that males and females show different sensitivities in mid-to-high latitudes, which might evidence diverging life cycles in these environments.
To study the genetic mechanisms which lead to this smooth variation in sensitivity, the team sequenced the genes of 21 different species and looked for trends using a “monophyletic window” approach, a more stringent measure of genetic differences than conventional approaches, but one which can deal with small sample sizes. They discovered that differing expression of the timeless ( tim ) gene was associated with the variations seen in female diapause sensitivity. This adds to growing evidence that genes associated with circadian rhythm are implicated in the induction of diapause.
The team’s findings are an important step forward in our understanding of the molecular mechanisms behind diapause and lights the way for how diapause in other animals might also be quantified, studied, and understood.
This work was supported by JSPS KAKENHI Grant Numbers 23K27221, 24KJ0181, 22H05073, and 22KJ2552.
Molecular Ecology
Geographic Divergence and the Genomic Basis of Reproductive Diapause in Drosophila triauraria
30-Jan-2026