Same thing from Discovery news:
http://dsc.discovery.com/news/2007/07/12...=20070712160030'It is not yet clear whether the suppressor gene emerged from a chance mutation from within the local population, or if it was introduced by migratory Southeast Asian butterflies in which the mutation had already been established.
"But regardless of which of the two sources of the suppressor gene is correct, natural selection is the next step. The suppressor gene allows infected females to produce males, these males will mate with many, many females and the suppressor gene will therefore be in more and more individuals over generations," Charlat explained.
Overall, the waxing and waning fortunes of the male Blue Moon butterfly shows that not only how fast species can evolve, or adapt, but just how important parasites can be as evolutionary drivers, the authors said.
"In the case of H. bolina, we're witnessing an evolutionary arms race between the parasite and the host. This strengthens the view that parasites can be major drivers in evolution," said Charlat.'