If female butterflies are programmed to identify males of their species by the patterns of spots on their wings, how can new wing patterns evolve in males? The answer is that while females are predisposed to prefer a specific pattern, they learn to like flashier ones more, according to a new Yale University study. The study published online the week of June 11 in the Proceedings of the National Academy of Sciences gives a partial explanation of an evolutionary mystery.
The team studied the butterfly species Bicyclus anynana, which in the wild has two spots on its forewings (the tops of the wings). The researchers found that female butterflies of the species learn to prefer males with four spots on their forewings over those with two spots.