题目：Origins of mimicry: The case of doublesex as a supergene
the University of Chicago, Dept at Ecology & Evolution
摘要：Complex sexually dimorphic phenotypes, which are attracting growing interests from scientists, are pervasive in living organisms and diseases. The sex-limited mimicry is one of the most striking examples of sexual dimorphism in nature and widely spreads in the Asian swallowtail butterfly genus Papilio. Butterflies in this genus often display female-limited mimicry and sexual polymorphism/dimorphism. In multiple polymorphic species, the entire complex phenotype is controlled by a single Mendelian locus, also known as a “supergene”. However, there are almost no empirical data that address the genetic basis of a mimicry supergene, and furthermore, trace the origin and evolutionary history of supergene mimicry. In contrast to the long-held view that supergene is a cluster of tightly linked loci, our results reveal that a single gene, doublesex, can switch the entire wing pattern among mimicry phenotypes, and alternative splicing, expression differences, and protein sequence evolution are all involved in controlling the mimicry wing pattern. Also, we show a single evolutionary origin of supergene mimicry in the species group polytes, which has been maintained by ancient balancing selection and a deleterious genetic load, as well as a secondary loss of polymorphism in some lineages due to genetic drift and natural selection. Our results answer long-established questions related to supergene mimicry using a classic example of adaptation.