Decoding a butterfly’s colours

A research team from NUS Biological Sciences has produced new insights into the vibrant colours on the wings of the Painted Jezebel butterfly, and determined that red is a novel colour that originated within this lineage of butterfly and is potentially more effective in keeping predators at bay. The findings were published in PLOS ONE in January 2017.

The Painted Jezebel butterfly has bright yellow and red wing colours, and is commonly found in urban and forested landscapes throughout the Asia-Pacific region, including Singapore. In fact, the research team, comprising PhD candidate Jocelyn Wee and Associate Professor Antónia Monteiro, shared that it is also commonly spotted on NUS Kent Ridge Campus.

The team conducted field experiments at three sites across Singapore where the Painted Jezebel are naturally found — along Kent Ridge Road, Tampines Eco-Green and Jurong Eco Garden. Jocelyn constructed over 300 artificial paper models that depicted the Painted Jezebel with its wings held vertically over its body, simulating its natural resting position. She made five variants of the paper models, including a faithful colour representation of the Painted Jezebel, a greyscale model, as well as three more highlighting the red, yellow and black respectively. These paper models were then placed at the three sites and observed for signs of attacks from predators like birds.

Jocelyn with several artificial paper models of the Painted Jezebel that she created for her field experiments

The researchers found that paper models that were faithful colour representations of the Painted Jezebel suffered the least amount of attacks, followed by models with unaltered red patches, and models with unaltered yellow patches.

Jocelyn explained the significance. “The results of our field experiments showed that red and yellow on the ventral wings of the Painted Jezebel serve as warning signals to predators, and demonstrated how predators can play a critical role in affecting the evolution of warning colours within this particular butterfly genus,” she said.

The research team also mapped the wing colours of the 250 butterflies in the Delias genus, which the Painted Jezebel belongs to. Being the largest genus of butterflies yet having little colour variation between them was what piqued their curiosity to study the particular genus.

They observed that yellow and red appear almost exclusively on the exposed ventral wing surfaces, and that older lineages have mostly yellow, white and black wing markings, with red appearing as a novel trait in later lineages. This showed red to be a novel and potentially more effective protective colour for butterflies in the Delias genus.

This discovery raises further questions which the team is excited to explore. “I am interested in the genetics of colour,” said Assoc Prof Monteiro. “It would be interesting to figure out the genetic modifications that had to take place to produce this novel red pigment, and to understand the mechanistic basics of how colours or new pigments can evolve in organisms.”