BBC NEWS | Science/Nature | Butterfly unlocks evolution secret:
researchers studying a family of butterflies think they have witnessed a subtle process, which could be forcing a wedge between newly formed species.
The team, from Harvard University, US, discovered that closely related species living in the same geographical space displayed unusually distinct wing markings.
These wing colours apparently evolved as a sort of "team strip", allowing butterflies to easily identify the species of a potential mate.
This process, called "reinforcement", prevents closely related species from interbreeding thus driving them further apart genetically and promoting speciation.
Speciation at work. Evolutionary theory predicts this process, and experimental evidence bears it out.