PLASTICITY IN BUTTERFLY EGG SIZE: WHY LARGER OFFSPRING AT LOWER TEMPERATURES?

Abstract

Dividing sister pairs of the butterfly Bicyclus anynana (reared in a common environment) between high and low temperature shows that oviposition temperature induces a plastic response in egg size. Females at a lower temperature laid significantly larger (but fewer) eggs than their sisters kept at a higher temperature, whereas total reproductive investment increased with temperature. Cross-transfer experiments demonstrated that this plastic response in egg size is reversible. Interestingly, this pattern parallels an almost universal temperature-induced developmental response in ectotherm body size. In both cases, however, we do not yet understand the underlying mechanisms or the potential adaptive significance. By cross-transferring the experimentally manipulated eggs between temperatures, we showed that the larger eggs produced at a lower temperature had a higher hatching success, and yielded larger hatchlings with a slightly higher probability of reaching maturity and shorter larval development time (at ...