Non-adaptive origins of interactome complexity

Area of Science:

• Evolutionary biology
• Genomics
• Molecular evolution

Background:

• Transitions to smaller population sizes (prokaryotes, unicellular/multicellular eukaryotes) amplify genetic drift and mutation effects.
• Reduced selection efficiency in smaller populations can drive non-adaptive genomic changes.
• The influence of genetic drift on subcellular and cellular phylogenetic diversity remains a key question.

Purpose of the Study:

• To investigate the relationship between the power of random genetic drift and protein subunit structural integrity.
• To explore the role of population size in shaping long-term phenotypic evolution.
• To test the hypothesis that non-adaptive mechanisms contribute to the evolution of complex protein interactions.

Main Methods:

• Phylogenetic analysis across diverse organisms.
• Comparative analysis of protein subunit structure and population genetics data.
• Modeling the effects of genetic drift and mutation accumulation.

Main Results:

• A broad inverse correlation was observed between the power of genetic drift and protein subunit structural integrity.
• Populations with stronger drift exhibit reduced protein structural integrity.
• This suggests that drift-induced accumulation of deleterious mutations may favor stabilizing interactions.

Conclusions:

• Population size and the resulting power of genetic drift are significant factors in molecular evolution.
• Non-adaptive processes, driven by drift, can play a crucial role in the emergence of complex protein architectures and interactions.
• This provides a potential mechanism for the initial steps in the evolution of phenotypic diversity.