US researchers have discovered that a single gene controls the complex wing patterns in female swallowtail butterflies - animals known for their mimicry of other toxic butterfly species, to avoid being eaten - publishing their findings in the journal Nature. The gene, called doublesex, is already known for being involved in controlling sex differences in insects, but the scientists have found that it’s responsible for the butterflies’ wing patterns too.
The discovery is surprising as such complex patterns might be expected to be the result of many genes working together, rather than just one. To find the gene, the researchers carefully mapped the DNA of more than 500 butterflies, and sequenced the genomes of 30, looking for specific genes linked to mimicking wing patterns. Further experiments showed that the gene is switched on exactly in the same places as the resulting pattern on the butterfly’s wings. It’s particularly interesting that the gene is involved in wing patterning and sex differences, as only female swallowtails show mimicry, so there may be a broader importance for the gene in determining the difference between male and female butterflies.