A butterfly in the South Pacific has just evolved its way out of extinction in just a year, displaying the fastest evolutionary change yet observed. The blue moon butterfly had been decimated by a parasite, but has now evolved a resistance to the bacteria.
The butterfly was able to evolve so quickly because the bacteria only affected males of the species. The male:female ratio, usually 50:50 fell to 1:99, allowing those males with a resistance gene to breed with many more females than otherwise would have been the case.
Similar instances of skewed sex ratios in butterflies due to parasites being corrected by rapid evolution has been observed before. However, never has it been seen so dramatically or so quickly. Scientists have labelled the phenomenon the Red Queen principle of evolution, named after the Lewis Carroll character, who ran faster and faster only to stay in the same place.