Gene Expression Evolves under a House-of-Cards Model of Stabilizing Selection

Area of Science:

• Evolutionary biology
• Genomics
• Quantitative genetics

Background:

• Divergence in gene regulation is a key hypothesis for phenotypic evolution.
• The precise role of natural selection in shaping gene expression variation remains debated.
• Theoretical predictions for long-term selection effects on gene expression are needed.

Purpose of the Study:

• To differentiate hypotheses on stabilizing selection and mutation in shaping natural gene expression variation.
• To provide accessible theoretical predictions for the effect of selection on gene expression over long timescales.
• To assess the generality of evolutionary models for gene expression.

Main Methods:

• Utilized diverse genomic data, including expression profiles from natural variation and mutation accumulation lines.
• Incorporated empirical estimates of genomic mutation rates.
• Employed inferences of genetic architecture to test evolutionary models.

Main Results:

• Gene expression evolution is well-described by the House-of-Cards (HC) model.
• The HC model's fit is robust despite variations in the number of gene-controlling loci.
• Results are consistent across evolutionary time (yeast to fruit fly), indicating generality.
• Mutational effects on gene expression are relatively large.
• Selection imposes modest constraints on most gene expression levels, but regulatory evolution potential is high.

Conclusions:

• The House-of-Cards model provides a general framework for understanding gene expression evolution.
• Large mutational effects and modest selective constraints characterize gene expression evolution.
• Empirical data support high potential for regulatory evolution.
• Further data collection is encouraged for more nuanced HC model parameterizations.