The Genetics and Evolution of Leaf Mimicry in Kallima Butterflies

Leaf mimicry is a fascinating phenomenon in nature. Among the widespread leaf mimics, Kallima butterflies display cryptic dead leaf-like wing patterns and have served as a classic case of protective resemblance supporting the theory of natural selection. Here, we integrated multi-omics data analyses and functional validation to uncover the evolutionary history of Kallima butterflies and investigated the genetic basis of their leaf mimicry. We found evidence for the differentiation and radiation of Kallima butterflies from Eastern Himalaya to East Asia and Southeast Asia. Moreover, we show that the leaf wing polymorphism is controlled by the wing patterning gene, cortex, which has been maintained in the Kallima genus due to balancing selection. Further, we demonstrate the involvement of another wing toolkit gene, WntA, in main leaf vein patterning resulting from a shared ancestral character. Our results reveal that the Kallima leaf wing formation is a typical case of Darwinian gradualism.