The quantitative genetic consequences of pleiotropy under stabilizing and directional selection

Area of Science:

• Evolutionary genetics
• Quantitative genetics
• Population genetics

Background:

• Pleiotropic mutations affect multiple phenotypic traits.
• Understanding trait independence is crucial for evolutionary models.
• Existing models like Lande's (1980) and Turelli's (1985) offer different predictions.

Purpose of the Study:

• Investigate phenotypic character independence under pleiotropic and nonpleiotropic mutations.
• Evaluate predictions of intermediate evolutionary models.
• Determine the typicality of multivariate normal and house-of-cards models.

Main Methods:

• Generalization of Slatkin's (1987) stepwise mutation model.
• Analysis under stabilizing and directional selection.
• Examination of mutation types and their impact on trait covariance.

Main Results:

• Under stabilizing selection, trait variance can depend on the other trait's selection strength, influenced by mutation types.
• Under directional selection, genetic covariance can increase significantly, depending on assumed mutation types.
• Neither Lande's nor Turelli's models consistently predict outcomes for intermediate models.

Conclusions:

• The type of mutations significantly influences trait independence and covariance.
• Neither the multivariate normal nor house-of-cards models are universally applicable.
• General conclusions about complex evolutionary models cannot be reliably drawn from these simpler models.