Does predation maintain eyespot plasticity in Bicyclus anynana?
The butterfly Bicyclus anynana exhibits phenotypic plasticity involving the wet-season phenotype, which possesses marginal eyespots on the ventral surface of the wings, and the dry-season form, which lacks these eyespots. We examined the adaptive value of phenotypic plasticity of B. anynana in relation to the defence mechanisms of crypsis and deflection. We assessed the visibility differences between spotless and spotted butterflies against backgrounds of brown (dry season) or green (wet season) leaves. Spotless butterflies were highly cryptic and less predated by adult bird predators than were spotted ones when presented against brown leaf litter. However, the advantage of crypsis disappeared in the wet-season habitat as both forms were equally visible. In later experiments, naive birds presented with resting butterflies in the wet-season habitat tended to learn more rapidly to capture spotless butterflies, suggesting a slight selective advantage of possessing eyespots. Moreover, marg
