The Papilio Genome Project to Understand Various Types of Mimicry

Body coloration is an ecologically important trait that is often involved in prey–predator interactions through mimicry and crypsis. Although this subject has attracted the interest of biologists and the general public, our scientific knowledge on the subject remains fragmentary. The swallowtail butterflies show various type of protective mimicry. (1) The caterpillar of Papilio xuthus show the drastic change from the bird dropping mimetic pattern to the greenish cryptic pattern. The color patterns of Papilio larva are also diversified even among closely related species. (2) In the pupa of P. xuthus, two types of cryptic colors, brown or green, are selected in response to the larval environment. (3) The female of P. polytes has two forms, one of which mimics to the model poisonous butterfly Pachliopta aristolochiae to avoid the contact with the predator birds. This Batesian mimicry is known to be controlled by only one genetic locus. To identify the genes involved in these phenomena at the larval, pupal and adult stages, we have so far analyzed the gene expression comprehensively by several methods such as subtraction, EST, microarray and WISH. Through these analyses, we found that cis-regulatory changes of some key genes (transcription factors and morphogens) are essential for each event. To further clarify the detailed molecular bases for the networks, we have tried to reveal the whole genome sequence of P. xuthus and P. polytes, using next generation sequencers. I would like to introduce the current state for these genome projects.