RESPONSE TO SELECTION IN PARTIALLY SELF-FERTILIZING POPULATIONS. II. SELECTION ON MULTIPLE TRAITS

Area of Science:

• Evolutionary Biology
• Quantitative Genetics

Background:

• Phenotypic correlations between traits can arise from various sources.
• Understanding these correlations is crucial for predicting evolutionary trajectories.

Purpose of the Study:

• To generalize the structured linear model (SLM) for analyzing selection on multiple, correlated traits.
• To differentiate and characterize four distinct causes of phenotypic correlations.

Main Methods:

• The structured linear model (SLM) was extended to incorporate multiple traits.
• Four sources of phenotypic correlation were identified: environmental covariance, identity disequilibrium, pleiotropy, and linkage disequilibrium.
• Parameters for evolutionary rates were derived, distinguishing between rapidly evolving (disequilibrium-based) and slowly evolving (pleiotropy/environment-based) correlations.

Main Results:

• The SLM now quantifies four distinct sources of phenotypic correlation.
• Correlations from identity and linkage disequilibrium are sensitive to mating systems and selection, evolving rapidly.
• Correlations from pleiotropy and environmental covariance evolve slowly and can be estimated from relative comparisons, revealing novel inbreeding covariance components.

Conclusions:

• The generalized SLM provides a framework for understanding multitrait evolution.
• Inbreeding and genetic dominance significantly influence evolutionary patterns through novel covariance components.
• These components may substantially alter multitrait evolution in self-fertilizing populations.