Dorsal and ventral views of male Bicyclus anynana

A male African squinting bush brown (Bicyclus anynana) sports much more elaborate patterns on one side of its wings than the other. Credit: Anupama Prakash and LepData

Developmental biology

Explaining butterflies’ double-sided splendour

A gene governs the appearance of eyespots and other ornaments.

Many butterflies have two wing patterns: one each for the upper and lower sides of the wing. Now researchers have singled out a gene that helps to create this double-sided design.

Anupama Prakash and Antónia Monteiro at the National University of Singapore found that a gene called apterous A triggers the variation from one side of the wing to the other. The gene was already known to contribute to wing development in other insects, such as beetles. The authors discovered that in a butterfly called the African squinting bush brown (Bicyclus anynana), the gene is active only on upper-wing surfaces. When the team mutated the gene in larvae, the resulting butterflies had upper-wing surfaces similar to the lower ones.

The gene quashes the appearance of some wing patterns, such as eyespots and a white stripe, the authors say.

This suggests that mutations in the gene may have had an important role in butterfly evolution.