A simple model of co-evolutionary dynamics caused by epistatic selection

Area of Science:

• Genetics
• Evolutionary Biology
• Molecular Evolution

Background:

• Epistasis describes how a mutation's effect depends on the genetic background.
• It plays a role in species barrier evolution and genetic architecture.
• Epistasis is proposed to influence co-evolutionary patterns in interacting genes.

Purpose of the Study:

• To formalize epistasis's role in molecular co-evolution using a simple model.
• To investigate how gene substitution influences fitness rank at other loci.
• To analyze co-evolutionary dynamics between interacting genes.

Main Methods:

• Developed a model representing epistasis as one gene substitution affecting another's allele fitness rank.
• Simulated evolutionary adaptive walks between interacting loci.
• Assessed the correlation between evolutionary rates and epistatic effects.

Main Results:

• Epistasis leads to co-evolution, evidenced by correlated lengths of adaptive walks between interacting loci.
• Simultaneous episodes of elevated evolutionary rates in both loci drive this correlation.
• The probability of a substitution having an epistatic effect is the primary driver of co-evolutionary correlation.

Conclusions:

• Epistasis can induce co-evolutionary patterns in molecular evolution.
• Covariance in evolutionary rates among loci may serve as a detectable signature of epistasis.
• Model robustness suggests these findings are generalizable to various epistatic scenarios.