DNA Switch Enables Tropical Butterflies to Adapt Wing Patterns

Researchers at the National University of Singapore (NUS) have unveiled a crucial DNA “switch” that enables tropical butterflies to alter the size of their wing eyespots in response to seasonal temperature variations. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, sheds light on the evolutionary mechanisms behind environmental adaptability, with implications for understanding how species may cope with climate change.

The study focuses on the Bicyclus anynana, a butterfly species known for its striking seasonal differences. In the wet season, these butterflies exhibit larger eyespots, while in the dry season, the sizes shrink. This seasonal adaptability, termed plasticity, plays a vital role in enhancing survival rates in varying environmental conditions.

Insects, including butterflies, have long fascinated scientists due to their remarkable ability to adapt to their surroundings, often displaying changes in color or pattern with the passing seasons. Although the phenomenon of plasticity has been recognized, its genetic underpinnings have remained largely elusive.

Led by Professor Antónia Monteiro from the NUS Department of Biological Sciences, the research team identified a specific stretch of DNA responsible for these seasonal adjustments. Previous studies indicated that caterpillar rearing temperatures significantly influence eyespot development, a response particularly pronounced in the satyrid group of butterflies, characterized by their predominantly brown wings adorned with distinctive eyespots.

The current research pinpointed a pivotal gene called Antennapedia (Antp), which governs the development of eyespots in satyrid butterflies. The team discovered that the activity of this gene varies based on the rearing temperatures of the butterflies. Disrupting the gene’s activity in two different satyrid species resulted in smaller eyespots, particularly under warmer conditions, thereby confirming its critical role in seasonal size adjustments.

Additionally, the scientists uncovered a novel DNA switch, or “promoter,” unique to satyrid butterflies. This switch activates the Antp gene specifically within the cells responsible for forming the eyespots. When this switch was disabled, the butterflies’ ability to modify eyespot size in response to temperature changes was significantly impaired, highlighting its importance in the evolution of seasonal flexibility.

Dr. Tian Shen, the lead author of the study and a former graduate student and postdoctoral fellow at NUS, remarked on the significance of the findings. “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,” he stated.

This research not only enhances our understanding of butterfly adaptation but also raises important questions about the genetic mechanisms that may aid various species in surviving the effects of climate change. The intricate relationship between genetics and environmental response revealed in this study underscores the need for ongoing research into how organisms can thrive in increasingly variable climates.