Oakleaf butterflies of the genus Kallima occur in mountains and lowland regions across Asia. The wing patterns of these butterflies vary across species but they all look like dead, brown leaves. Writing in Cell in August 2022, Wang et al. studied the evolutionary history and genetic basis of leaf masquerade mimicry in Kallima butterflies. Using phylogenetic and demographic analyses based on genome sequences of several species, the authors showed that Kallima butterflies differentiated in the eastern Himalayas and then colonized the continental islands of Hainan and Taiwan as well as islands such as Java, Sumatra and Borneo, which were connected to the continent during the Pleistocene epoch. The authors then focused on Kallima inachus chinensis to identify the genetic basis of their wing pattern variation. Using a combination of genome wide association analysis, gene expression, chromatin interaction analyses and genome editing, they pinned down cortex, a gene that is involved in wing morphogenesis in other lepidopterans, as a major controller of leaf wing polymorphism in Kallima butterflies. The authors found that chromosomal rearrangements across the cortex region give rise to different genotypes that segregate in K. i. chinensis populations. Finally, using population genetic analysis, the authors show that long-term balancing selection has maintained Kallima leaf wing polymorphism.
We were impressed by how comprehensive this study was, linking macro- and microevolutionary perspectives in a new model species from a less-studied region of the globe, to understand the evolution of mimicry.
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