Cooler butterflies lay larger eggs: developmental plasticity versus acclimation.

Area of Science:

• * Evolutionary biology
• * Developmental biology
• * Animal physiology

Background:

• * Environmental factors significantly influence phenotypic traits in animals.
• * Temperature-dependent plasticity is crucial for adaptation in ectotherms.
• * Understanding egg size plasticity is vital for predicting population dynamics.

Purpose of the Study:

• * To investigate the impact of developmental and oviposition temperatures on butterfly egg size.
• * To determine the reversibility of temperature-induced effects on egg size.
• * To compare plasticity during development versus acclimation in adults.

Main Methods:

• * Full factorial design analyzing maternal/paternal developmental temperature and female oviposition temperature.
• * Rearing the butterfly *Bicyclus anynana* at two distinct temperature regimes.
• * Measuring egg size at two time points: immediately after temperature assignment and after a 10-day acclimation period.

Main Results:

• * Initially, female developmental temperature affected egg size; lower temperatures yielded larger eggs.
• * After acclimation, oviposition temperature became the primary determinant of egg size; lower temperatures produced larger eggs.
• * Male developmental temperature had no significant effect on egg size.
• * Developmental plasticity and adult acclimation showed similar patterns of egg size plasticity.

Conclusions:

• * Temperature effects on egg size are largely reversible, challenging assumptions about fixed developmental impacts.
• * Adult acclimation can mirror developmental plasticity, suggesting flexible environmental responses.
• * The adaptive significance of plastic responses is more critical than the stage at which plasticity occurs.