Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes.

Area of Science:

• Evolutionary biology
• Genetics
• Cell biology

Background:

• Eukaryotes possess multiple asexual cytoplasmic genomes, including mitochondria and plastids.
• Asexual genomes are theoretically predicted to have impaired adaptive evolution due to lack of recombination.
• Empirical data suggests higher adaptive evolution rates in cytoplasmic genomes than theory predicts.

Purpose of the Study:

• To investigate the mechanisms enabling effective adaptive evolution in asexual cytoplasmic genomes.
• To computationally model the impact of cytoplasmic genome biology on evolutionary trajectories.
• To explain the discrepancy between theoretical predictions and empirical observations of cytoplasmic genome evolution.

Main Methods:

• Development and analysis of a computational model.
• Simulation of cytoplasmic genome inheritance patterns (uniparental vs. biparental).
• Assessment of the effects of genetic drift, clonal interference, Muller's ratchet, and genetic hitchhiking.

Main Results:

• Uniparental inheritance significantly enhances adaptive evolution of cytoplasmic genomes.
• Uniparental inheritance reduces clonal interference, promoting beneficial substitutions.
• Uniparental inheritance facilitates selection against deleterious mutations and reduces genetic hitchhiking.
• Biparental inheritance with bottlenecks can aid adaptation but is less efficient than uniparental inheritance.

Conclusions:

• The unique biology of cytoplasmic genomes, particularly uniparental inheritance, drives effective adaptive evolution.
• Uniparental inheritance optimizes the balance of beneficial versus deleterious substitutions.
• Findings reconcile theoretical expectations with empirical evidence on cytoplasmic genome evolution.