Genetic variance in reproductive timing contributes to trait evolvability.

Area of Science:

• Evolutionary biology
• Quantitative genetics
• Life history theory

Background:

• Additive genetic variance traditionally measures evolvability.
• Evolvability in overlapping generations is influenced by parental age at reproduction.
• Early reproducing genotypes evolve faster.

Purpose of the Study:

• To investigate how directional selection on phenotypic traits affects developmental timing and evolvability.
• To determine the contribution of genetic variance in reproductive age to trait evolvability.
• To analyze the impact of selection strength on generation time.

Main Methods:

• Individual-based simulations for proof of principle.
• Formalization within a quantitative genetic framework.
• Extension of the breeder's equation.

Main Results:

• Directional selection on a trait links it to reproductive age and developmental timing.
• Genetic covariance between selected traits and reproductive age accelerates evolutionary response.
• Genetic variance in reproductive age contributes to evolvability, even for initially unrelated traits.
• Stable generation time requires intermediate selection strength for later reproduction.

Conclusions:

• Evolvability is influenced by both trait genetic variance and reproductive age genetic variance.
• Strong selection episodes tend to shorten average generation time.
• Findings have implications for understanding senescence and life history evolution.