Flashy wing colours for protection
NUS evolutionary biologists have shown experimentally that red and yellow colours protect painted jezebel butterflies from predation.
Butterflies of the South Asian and Australian genus Delias possess striking colours on the ventral wings that are presumed to serve as warning signals of toxicity to predators. However, this has not been shown empirically. A team led by Prof Antónia MONTEIRO, together with her Ph.D. student Jocelyn WEE, experimentally tested whether the wing colours of one member of this diverse genus, Delias hyparete, function as warning signals. A series of field experiments using live mealworms as “bait” attached to paper wings designed to be either a faithful colour representation of D. hyparete, or with all or some of its colours converted to grey scale, showed that red and yellow colours confer protection from predators.
Faithful models of D. hyparetesuffered the least amount of attacks, followed by grey scale models with unaltered red patches, and then by grey-scale models with unaltered yellow patches. Hence, red and yellow colours appear to serve as warning signals to predators. The team followed up on their results by mapping the dorsal and ventral colouration onto a phylogeny of Delias (related butterfly species). Yellow and red colours were observed to appear almost exclusively on the exposed ventral wing surfaces. Older lineages have mostly yellow markings, with red appearing in derived lineages. Red therefore appears to be a novel and potentially more effective protective colour to members of this lineage of butterflies.
This study focuses attention on the role of bright colours on the wings of butterflies and the role of predation in shaping the evolution and origin of novel wing colours. In future, the team hopes to focus on resolving the genetic pathways that underlie the evolution of wing colours and complex patterns across the genus Delias.
The role of wing colours in the painted jezebel (Delias hyparete) butterfly was examined with the use of altered or faithful coloured paper models attached to a live mealworm serving as bait. [Image credit: Antónia Monteiro and Jocelyn Wee]
Reference
Wee J; Monteiro A*, “Yellow and the novel aposematic signal, red, protect Delias butterflies from predators” PLOS ONE Volume: 12 Issue: 1 Article Number: e0168243 DOI: 10.1371/journal.pone.0168243 Published: 2017.