AsianScientist (Apr. 22, 2015) – Researchers have uncovered the genetic basis of Batesian mimicry, the process by which harmless species imitate more dangerous relatives to avoid predation. Their study has been published in Nature Genetics.
The swallowtail butterfly Papilio polytes, which inhabits the Okinawa islands, is known to mimic its unpalatable relative Pachliopta aristolochiae. Interestingly, this Batesian mimicry is only seen in female Papilio polytes butterflies and is linked to the doublesex gene which is usually involved in sex differentiation. However, the precise molecular mechanism of Batesian mimicry remains unknown.
In the present study, researchers from the University of Tokyo studied the whole genome sequences of the unpalatable Pachliopta aristolochiae, Papilio polytes and the closely related Papilio xuthus which does not show Batesian mimicry.
Professor Fujiwara Haruhiko, project researcher Nishikawa Shinichi at the Graduate School of Frontier Sciences and their colleagues determined that the region responsible for the mimicry is a supergene, a large region including multiple genes covering more than 130kb of the genome and includes the doublesex gene.
The orientation of the supergene on the chromosome of the mimetic female was the reverse of the non-mimetic female. The researchers speculate that this inverted structure was produced some tens of millions of years ago. In addition, the research group showed that the doublesex gene from the mimetic female but not from the non-mimetic female caused the mimetic wing color pattern.
This research solves the mystery of why Batesian mimicry is limited to females and is the first to demonstrate the complete structure and function of a supergene.
The article can be found at: Nishikawa et al. (2015) A Genetic Mechanism For Female-limited Batesian Mimicry In Papilio Butterfly.
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Source: The University of Tokyo.
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