Polymorphic Butterfly Reveals the Missing Link in Ecological Speciation

Abstract

Butterfly Apartheid Heliconius butterflies show differences in mimetic color patterns across geographic races associated with patterns of assortative mating, suggesting that ecological speciation may be ongoing. Chamberlain et al. (p. 847 ) demonstrate assortative mating on the basis of color pattern mimicry that generates reproductive isolation between Heliconius cydno species and subspecies within polymorphic populations in Ecuador. Furthermore, it appears that these traits are controlled by a single gene that affects color pigment in wing pattern formation and vision. Thus, these butterflies are indeed in the early stages of reproductive isolation that is being driven by an ecological trait, allowing observation of an incipient speciation event.