NUS Researchers Discover DNA Switch in Tropical Butterflies

Scientists from the National University of Singapore (NUS) have unveiled a crucial DNA switch that enables tropical butterflies to modify their wing patterns with changing seasons. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, could advance understanding of how species adapt to shifting environmental conditions.

The research, led by Professor Antónia Monteiro from the NUS Department of Biological Sciences, focuses on the African butterfly species Bicyclus anynana. These butterflies exhibit distinct differences in wing eyespots, which vary significantly between the wet and dry seasons. During the wet season, they develop larger eyespots, while these reduce in size during the dry season. This adaptation enhances their survival in diverse climates.

Understanding Seasonal Adaptation

Previous studies indicated that the temperature at which caterpillars develop significantly influences the size of these eyespots. Notably, this temperature response is unique to the satyrid group of butterflies, which are characterized by their predominantly brown wings adorned with distinctive eyespots. The latest findings build on this body of work by identifying a key regulatory gene, known as Antennapedia (Antp), responsible for controlling the size of these eyespots.

The team observed that the activity of the Antp gene fluctuates based on the temperature conditions experienced by the butterflies during their development. By disrupting the function of this gene in two different satyrid species, researchers noted a marked reduction in eyespot size, particularly when the butterflies were raised in warmer climates. This confirmed Antp’s pivotal role in facilitating seasonal size changes.

New Insights into Genetic Flexibility

In addition to identifying the Antp gene, the research team discovered a previously unrecognized DNA switch, referred to as a “promoter,” that is unique to satyrid butterflies. This switch activates the Antp gene specifically in the cells responsible for eyespot development. When this genetic element was disabled, the butterflies lost their ability to adjust their eyespot size according to temperature changes, underscoring its importance in the evolution of seasonal adaptability.

Dr. Tian Shen, the first author of the study and a former graduate student and postdoctoral fellow at NUS, expressed his astonishment at how a simple genetic switch can drive complex environmental sensitivity across a wide range of insects. He noted, “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 enhances our understanding of insect adaptability but also highlights the potential for genetic studies to contribute to conservation efforts as global climates continue to change. The implications of this work extend beyond butterflies, potentially offering insights applicable to various species facing environmental pressures.