Adaptation of a tropical butterfly to a temperate climate

Developmental plasticity enables organisms to cope with environmental heterogeneity, such as seasonal variation in climatic conditions, and is thought to affect a species’ capability to adapt to environments with novel seasonal and ecological dynamics. We studied developmental plasticity of the widespread tropical butterfly, Bicyclus safitza, which reaches the southern edge of its distribution in the temperate zone of South Africa. In wet–dry seasonal environments in tropical Africa, adults of Bicyclus butterflies are present all year round and exhibit discrete seasonal forms in alternating generations. We demonstrate that a population that colonized a more temperate climate region has adop…

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 disappea…

Adaptation of a tropical butterfly to a temperate climate

Significance of butterfly eyespots as an anti-predator device in ground-based and aerial attacks

Many butterfly genera are characterised by the presence of marginal eyespots on their wings. One hypothesis to account for an occurrence of eyespots is that these wing pattern elements are partly the outcome of visual selection by predators. Bicyclus anynana (Satyrinae) has underside spotting on its wings but there is also a seasonal form in which the eyespots are reduced in size or totally absent. This natural variation gives us a useful tool to test the hypothesis that marginal eyespot patterns can decoy the attacking predator by, at least sometimes, diverting attack from vital body parts to the edges of the wings. We used lizards, Anolis carolinensis, and pied flycatchers, Ficedula hypol…