Evolution favors protein mutational robustness in sufficiently large populations

Area of Science:

• Evolutionary Biology
• Molecular Evolution
• Biophysics

Background:

• Investigates whether evolution selects for traits like mutational robustness and evolvability.
• These traits benefit future evolution but not necessarily individual organisms.
• Proteins vary in robustness and evolvability, but selection for these traits is unclear.

Purpose of the Study:

• To experimentally demonstrate if evolution favors protein mutational robustness.
• To determine the role of population size in the evolution of protein properties.

Main Methods:

• Neutral evolution of cytochrome P450 proteins in laboratory populations of varying sizes.
• Identical selection pressures and mutation rates were maintained across populations.
• Mathematical theory was used to analyze protein behavior on neutral networks.

Main Results:

• Larger, more polymorphic populations evolved proteins with significantly higher mutational robustness.
• Proteins from larger populations also exhibited increased stability.
• Observed increases in robustness and stability correlated with protein network occupancy.

Conclusions:

• First experimental evidence shows evolution favors mutational robustness and stability in large populations.
• This phenomenon may explain the robustness and evolvability of viruses and bacteria.
• Suggests population size is a key factor in the evolution of protein adaptive potential.