alithea
Walk through the rainforests of Ecuador and you might encounter a beautiful butterfly called Heliconius cydno. It's extremely varied in its colours. Even among one subspecies, H.cydno alithea, you can find individuals with white wingbands and those with yellow. Despite their different hues, they are still the same species... but probably not for much longer.
Even though the two forms are genetically similar and live in the same area, Nicola Chamberlain from Harvard University has found that one of them - the yellow version - has developed a preference for mating with butterflies of its own…