Bright bands of deep blue, black, and orange can be seen on the top side of the Kallima butterfly’s wings. The undersides of this butterfly’s wings, which are hues of dull brown that exactly mirror a dead leaf and provide a sharp contrast when the butterfly flaps its wings, serve as a deterrent to predators.
In a study that appears in the journal Cell on August 1, researchers identify the gene that causes Kallima butterflies to resemble leaves and describe what these implications for our understanding of their evolutionary history.
“Butterfly wings have relatively simple structures, but this simple structure is responsible for some very complex functions: locomotion, thermoregulation, mate preference, and predator avoidance,” says Wei Zhang, a butterfly researcher at Peking University in China. “Because these wings are structurally simple but functionally complex, I think butterfly wings are the ideal system to address multiple evolutionary questions.”
The scientists gathered Kallima samples from 36 distinct species around Asia in order to comprehend the evolution and genetics underlying the oak leaf butterfly’s extraordinary capacity for self-masking.
After sequencing the genomes of these butterflies, researchers focused on a gene called cortex that appeared to be in charge of the various leaf patterns. The butterfly population is undergoing intriguing morphological changes as a result of the stresses of evolution on this gene.
We generally focus on biodiversity at a macroevolutionary level. But we seldom have cases that illustrate in detail how species diversity and genetic diversity originated in such a diversity hotspot.Wei Zhang
“This leaf wing polymorphism has been maintained in multiple Kallima species, but different species may have different phenotype frequencies,” says Zhang. “I think this is due to the proliferation of specific plants in particular habitats, so the butterflies will gain more protective benefits by having different frequencies of wing phenotypes.”
The researchers concentrated on the eastern Himalayas as a center for Kallima butterfly diversification. They were able to investigate the evolution on a smaller scale than usual since they discovered so much variation in one region.
“We generally focus on biodiversity at a macroevolutionary level,” says Zhang. “But we seldom have cases that illustrate in detail how species diversity and genetic diversity originated in such a diversity hotspot.”
Zhang and her team plan to keep investigating how wing patterns and coloring alter in various habitats and with various plant species.
“We would like to understand how these genes facilitate, and originated, such beautiful diversifying wing patterns,” she says.
This project was supported by the Beijing Natural Science Foundation, the National Natural Science Foundation of China, the Peking-Tsinghua Center for Life Science, the State Key Laboratory of Protein and Plant Gene Research, Qidong-SLS Innovation Fund, the Second Tibetan Plateau Scientific Expedition and Research program, the Major Special Program of Tibet Autonomous Region, the Chinese Institute for Brain Research, and the Strategic Priority Research Program of the Chinese Academy of Sciences.