Environmental dependence of genetic constraint

Area of Science:

• Evolutionary Biology
• Molecular Biology
• Genetics

Background:

• Epistatic interactions, crucial for evolutionary constraints, are typically studied under constant environmental conditions.
• Environmental variability can significantly influence epistasis, thereby altering genetic constraints on evolution.
• Understanding how environmental changes affect evolutionary trajectories is vital for predicting adaptation.

Purpose of the Study:

• To investigate genetic constraints in adaptive evolution within variable environments.
• To examine the role of epistasis in the evolution of a novel regulatory function using the lac repressor (LacI) as a model.
• To analyze higher-order interactions between genetic and environmental changes.

Main Methods:

• Systematic reconstruction of mutational trajectories from wild-type LacI to three variants with inverse IPTG response.
• Analysis of higher-order interactions between genetic mutations and environmental factors.
• Development of a graphical method to analyze complex interactions between mutations and environmental changes.

Main Results:

• Epistasis is found to be strongly dependent on the environment.
• Environmental context determines the accessibility of essential mutational steps for adaptation.
• Interactions between mutations and environmental changes can be explained by effects on allostery and thermodynamic stability.

Conclusions:

• The environment fundamentally influences genetic constraints, impacting evolutionary dynamics.
• Environmental dependency of genetic constraints necessitates re-evaluation of phylogenetic data interpretation.
• Adaptive evolution in variable environments is shaped by environment-modulated epistasis.