Tropical Butterflies Adapt Wing Patterns Using Simple DNA Switch

Researchers from the National University of Singapore (NUS) have identified a simple DNA switch that enables tropical butterflies to change their wing patterns in response to seasonal temperature variations. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, provides new insights into how environmental sensitivity can evolve.

The study, led by Professor Antónia Monteiro, focuses on the African butterfly species Bicyclus anynana, which exhibits striking differences in wing patterns between the wet and dry seasons. In the wet season, these butterflies develop larger eyespots, while smaller eyespots are characteristic of the dry season. Such adaptations enhance survival in their respective environments.

Understanding Seasonal Plasticity

Insects often exhibit remarkable adaptations to their surroundings, including seasonal changes in coloration and size. This phenomenon, known as plasticity, plays a crucial role in survival, although its evolutionary origins have been less understood. Earlier research indicated that the temperature at which caterpillars are reared influences the size of their eyespots, particularly within the satyrid group of butterflies, which are predominantly brown and adorned with distinctive eyespots.

In the recent study, the research team identified a key gene named Antennapedia (Antp) that regulates the development of eyespots in satyrid butterflies. They discovered that the activity of this gene varies according to the temperature conditions experienced by the butterflies. Disruption of Antp in two distinct satyrid species resulted in a significant reduction in eyespot size, especially for those raised in warmer environments, demonstrating the gene’s essential role in seasonal adaptations.

The Role of Genetic Switches in Evolution

Additionally, the team uncovered a previously unknown DNA switch, referred to as a “promoter,” which is unique to satyrid butterflies. This switch activates the Antp gene specifically in the cells responsible for the central eyespots. When this switch was disabled, the butterflies’ capacity to adjust their eyespot size according to temperature was diminished. This finding suggests that such genetic elements are integral to the evolution of seasonal plasticity in these insects.

Dr. Tian Shen, the study’s lead author, emphasized the significance of these findings. “It is striking that a simple genetic switch can underlie complex environmental sensitivity across a broad group of insects,” he stated. He further noted that this research paves the way for future studies into how similar genetic mechanisms might influence adaptations in other species and offers insights that could aid conservation efforts in a changing climate.

As climate change continues to impact ecosystems globally, understanding the genetic basis of adaptation will be crucial. The research from NUS highlights the potential for simple genetic mechanisms to drive significant changes in species, shedding light on how various organisms might cope with environmental shifts.