Scientists at the National University of Singapore (NUS) have identified a crucial DNA switch that enables tropical butterflies to modify their wing patterns in response to seasonal temperature changes. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, provides new insights into how these insects adapt to their environments, particularly in the context of climate change.
The research team, led by Professor Antónia Monteiro from the NUS Department of Biological Sciences, focused on the African butterfly species Bicyclus anynana. These butterflies exhibit significant differences in wing patterns depending on whether they emerge during the dry or wet seasons. In the wet season, they develop larger eyespots, while the dry season sees a reduction in eyespot size. This seasonal plasticity enhances their survival chances in varying environmental conditions.
Understanding the genetic basis of this adaptation has been a challenge. Earlier studies indicated that the temperature experienced by caterpillars influences the size of their eyespots, a phenomenon unique to the satyrid butterfly group. This group is known for its brown wings adorned with distinctive eyespots, which play a role in their survival strategies.
In the recent study, the researchers identified a key gene known as Antennapedia (Antp), which regulates the development of eyespots in satyrid butterflies. The activity of this gene fluctuates based on the rearing temperatures of the butterflies. When the researchers disrupted the Antp gene in two different satyrid species, they observed a notable decrease in eyespot size, particularly at higher temperatures. This confirmed the gene’s pivotal role in facilitating seasonal adaptations.
Additionally, the team discovered a previously unknown DNA switch, or promoter, that is exclusive to satyrid butterflies. This switch activates the Antp gene specifically in the central cells of the eyespots. When the switch was disabled, the butterflies’ capacity to adjust their eyespot size in response to temperature changes was significantly compromised, underscoring its importance in the evolution of seasonal flexibility among these insects.
Dr. Tian Shen, the lead author of the study and a former graduate student and postdoctoral fellow at NUS, emphasized the significance of their findings. He stated, “It is striking that a simple genetic switch can underlie complex environmental sensitivity across a broad group of insects. These findings open the door to future research into the roles such switches play in shaping adaptations, and to insights that could inform conservation in a changing climate.”
This groundbreaking research not only sheds light on the evolutionary mechanisms behind environmental sensitivity in tropical butterflies but also lays the groundwork for future studies aimed at understanding how other species might adapt to rapidly changing climates. As global temperatures continue to rise, understanding these genetic frameworks will be crucial for conservation efforts aimed at protecting biodiversity.
