Evolution of Genetic Variance during Adaptive Radiation

Area of Science:

• Evolutionary biology
• Quantitative genetics
• Plant sciences

Background:

• Genetic correlations can constrain evolutionary trajectories by concentrating genetic variance.
• Rapid adaptive divergence into contrasting environments may be limited by genetic correlations.
• Natural selection may increase genetic variance in the direction of selection, potentially accelerating adaptation.

Purpose of the Study:

• To investigate the alignment between phenotypic divergence and genetic variance divergence in an Australian wildflower.
• To determine if natural selection alters the distribution of genetic variance during adaptive divergence.
• To explore the role of genetic variance in facilitating rapid adaptive radiation.

Main Methods:

• Examined phenotype mean and genetic variance divergence across four contrasting ecotypes.
• Analyzed multivariate phenotypic divergence along major axes (plant architecture, leaf traits).
• Assessed divergence in genetic variance for individual traits and multivariate distributions.

Main Results:

• Found divergence in multivariate phenotypic mean along two major axes.
• Observed ecotype-specific divergence in genetic variance levels and distributions.
• Demonstrated alignment between multivariate phenotypic mean divergence and genetic variance divergence.
• Associated phenotypic divergence with changes in trait combinations with substantial genetic variance.

Conclusions:

• Natural selection can modify the distribution of genetic variance underlying phenotypic traits.
• Increased genetic variance in the direction of selection can facilitate rapid adaptive divergence.
• Findings suggest a mechanism for accelerated adaptive radiation driven by selection-induced changes in genetic variance distribution.