Genetic variability at neutral markers, quantitative trait land trait in a subdivided population under selection

Area of Science:

• Population Genetics
• Evolutionary Biology
• Quantitative Genetics

Background:

• Understanding genetic variability in subdivided populations is crucial for evolutionary studies.
• Stabilizing and diversifying selection can impact genetic diversity at different levels: neutral markers, quantitative trait loci (QTL), and the trait itself.

Purpose of the Study:

• To investigate and compare genetic variability patterns at neutral markers, QTL, and traits under stabilizing and diversifying selection in a subdivided population.
• To analyze the influence of gene flow and selection intensity on the dynamics of genetic variation.

Main Methods:

• Employed a quantitative genetic model with additive effects to link genotypes and phenotypes.
• Utilized an analytical approach to compare diversity (H(S)) and differentiation (F(ST)) at QTL with genetic variance (V(W)) and differentiation (Q(ST)) for the trait.
• Conducted simulations to assess the effects of selection intensity, variance of optima, and migration rate in allogamous and selfing species.

Main Results:

• Observed contrasting dynamics of genetic variability at markers, QTL, and traits, influenced by gene flow and diversifying selection.
• The highest discrepancy among the three levels of genetic variation was found under strong diversifying selection and high gene flow.
• Diversifying selection can lead to significant heterogeneity among QTL, with only a subset showing allelic differentiation, while others act as neutral markers.

Conclusions:

• Genetic variability patterns are not uniform across neutral markers, QTL, and traits, especially under strong diversifying selection and high gene flow.
• The difference between QTL differentiation (F(ST)) and trait differentiation (Q(ST)) depends on covariance between QTL within and between demes.
• Diversifying selection can create a mosaic of genetic differentiation across the genome, impacting evolutionary trajectories.