Scientists from the National University of Singapore (NUS) have identified a DNA “switch” that enables tropical butterflies to alter their wing eyespot sizes based on seasonal temperature changes. This discovery, published in the journal Nature Ecology & Evolution on October 24, 2025, provides valuable insights into how environmental factors influence the evolution and adaptability of these insects.
The research team, led by Professor Antónia Monteiro from the NUS Department of Biological Sciences, focused on the Bicyclus anynana, a species known for its striking seasonal differences. In the wet season, these butterflies display larger eyespots, while in the dry season, the eyespots are significantly smaller. These variations are crucial for survival in different environments.
Prior studies demonstrated that the temperature at which caterpillars develop affects the size of their eyespots. Notably, this pronounced temperature response is specific to the satyrid group of butterflies, which are characterized by their predominantly brown wings and distinctive eyespots.
In their latest study, the researchers identified a crucial gene named Antennapedia (Antp), which regulates the development of eyespots in satyrid butterflies. The activity of this gene varies based on the temperature conditions during the butterflies’ development. Disrupting Antp’s function in two different satyrid species resulted in diminished eyespot sizes, particularly when the butterflies were raised in warmer conditions. This finding confirmed Antp’s significant role in the seasonal adaptation of eyespot sizes.
The team also discovered a unique DNA switch, or “promoter,” specific to satyrid butterflies. This switch activates the Antp gene in certain cells responsible for eyespot formation. When the switch was disabled, the butterflies demonstrated a reduced capacity to adjust their eyespot sizes according to temperature changes. This indicates that the genetic element plays a vital role in the evolution of seasonal flexibility among these species.
Dr. Tian Shen, the lead author of the research, emphasized the implications of their findings. “It is striking that a simple genetic switch can underlie complex environmental sensitivity across a broad group of insects,” he stated. “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.”
The research highlights the intricate relationship between genetics and environmental adaptability, shedding light on how organisms can evolve in response to their surroundings. As climate change continues to pose challenges to biodiversity, understanding these mechanisms may be vital for developing strategies aimed at conservation and the preservation of various species.
