The genetics of phenotypic plasticity. XVIII. Developmental limits restrict adaptive plasticity

Area of Science:

• Evolutionary biology
• Developmental biology
• Ecology

Background:

• Trait evolution post-environmental change relies on plasticity (reaction norms).
• Previous models assumed linear reaction norms, ignoring developmental limits.
• Sigmoidal reaction norms introduce developmental constraints on phenotypic plasticity.

Purpose of the Study:

• Investigate the effect of developmental limits (sigmoidal reaction norms) on evolutionary rescue.
• Analyze the evolution of plasticity and genetic assimilation under these constraints.
• Explore scenarios including costs of plasticity, developmental noise, and environmental variation.

Main Methods:

• Mathematical modeling of population evolution.
• Simulation of four scenarios: developmental limits, limits with plasticity cost, limits with noise, and limits with environmental variation.
• Analysis of reaction norm shapes and their impact on evolutionary outcomes.

Main Results:

• Increased phenotypic variation from plastic development enhanced evolutionary rescue probability.
• Limited plasticity range hindered adaptive plasticity evolution, favoring non-plastic gene evolution.
• Developmental constraints did not accelerate genetic assimilation, challenging existing theories.

Conclusions:

• Sigmoidal reaction norms are crucial for understanding evolutionary rescue and plasticity evolution.
• Developmental limits can necessitate the evolution of non-plastic traits for adaptation.
• Current theories may need revision to explain empirical observations of genetic assimilation.