NUS Discovers DNA Switch Enabling Seasonal Changes in Butterflies

Scientists at the National University of Singapore (NUS) have identified a genetic mechanism that allows tropical butterflies to adapt their wing patterns in response to seasonal temperature changes. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, provides insight into how these insects exhibit environmental sensitivity, potentially informing future adaptability strategies in the face 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 showcase distinct differences in wing eyespot sizes between the wet and dry seasons. In the wet season, they develop larger eyespots, while during the dry season, these spots shrink. Such seasonal plasticity enhances their survival in varying environments.

Understanding the mechanisms behind this adaptation has been challenging. The team previously established that caterpillar rearing temperatures influence eyespot size, a response unique to the satyrid group of butterflies, known for their predominantly brown wings decorated with distinctive eyespots.

Through their latest study, researchers pinpointed a master gene named Antennapedia (Antp), which regulates the development of eyespots in satyrid butterflies. They found that the activity level of this gene is influenced by the temperatures at which the butterflies are raised. When the team disrupted the activity of the Antp gene in two different satyrid species, they observed a significant reduction in eyespot size, particularly in warmer conditions. This confirmed the gene’s crucial role in seasonal adaptation.

In addition, the researchers identified a novel DNA switch, referred to as a “promoter,” that is unique to satyrid butterflies. This switch activates the Antp gene specifically in the central cells of the eyespots. By disabling this genetic element, the butterflies’ ability to adjust their eyespot size in response to temperature was significantly impaired, indicating its importance in the evolution of seasonal flexibility.

Dr. Tian Shen, the lead author of the study, emphasized the significance of the findings, stating, “It is striking that a simple genetic switch can underlie complex environmental sensitivity across a broad group of insects.” He noted that this research opens avenues for future exploration into how such genetic elements contribute to adaptations and conservation efforts in a changing climate.

The implications of this research extend beyond butterflies, suggesting that similar genetic switches could play critical roles in the adaptability of various species in response to environmental changes. As climate dynamics evolve, understanding these mechanisms will be vital for conservation strategies aimed at preserving biodiversity.