Intergenerational effects of dietary changes on trait means and variance

Area of Science:

• Evolutionary biology
• Ecology
• Genetics

Background:

• Environmental stress influences phenotypic traits.
• Trait variance is an evolvable feature with ecological and evolutionary significance.
• Intergenerational effects of stress on trait variance are understudied.

Purpose of the Study:

• To investigate how dietary stress affects both the mean and variance of morphological and reproductive traits in Daphnia across two generations.
• To explore potential mechanisms driving intergenerational impacts on trait variance.

Main Methods:

• Clonal Daphnia were subjected to high- (algae) or low-quality (cyanobacteria) diets across maternal and offspring generations.
• Eye size, body size, and reproductive output were measured in eight genotypes.
• Trait means and variances were analyzed for treatment-by-generation interactions.

Main Results:

• Low-quality diets reduced morphological trait size, with partial recovery observed.
• Eye and body size exhibited legacy effects from the maternal environment, while reproduction depended on current conditions.
• Trait-specific variance patterns emerged: eye size variance decreased under stress, body size variance increased across generations, and reproductive variance peaked following maternal stress.

Conclusions:

• Dietary stress significantly impacts Daphnia trait means and variances across generations.
• Condition transfer, anticipatory plasticity, and diversified bet-hedging are potential mechanisms for intergenerational effects on trait variance.
• Joint examination of trait mean and variance responses to stress is crucial for understanding phenotypic plasticity and evolutionary consequences.