Compensatory Evolution Following Deleterious Episodes of GC-biased Gene Conversion in Rodents.

Area of Science:

• Evolutionary biology
• Molecular evolution
• Genomics

Background:

• GC-biased gene conversion (gBGC) is an evolutionary mechanism linked to meiotic recombination.
• gBGC favors AT to GC substitutions, potentially accumulating deleterious mutations in proteins.
• Recombination hotspots in mammals undergo rapid turnover, leading to episodic gBGC.

Purpose of the Study:

• To investigate the occurrence and impact of compensatory evolution following gBGC episodes in Murinae rodents.
• To quantify the process of repairing deleterious mutations introduced by gBGC.

Main Methods:

• Phylogenetic analyses of approximately 70,000 coding exons in Murinae rodents.
• Identification of lineage-specific gBGC episodes by analyzing synonymous and nonsynonymous substitution patterns.
• Analysis of molecular evolution in downstream lineages to detect compensatory changes.

Main Results:

• Identified numerous exon-specific and lineage-specific gBGC episodes.
• Observed increased rates of potentially deleterious nonsynonymous AT to GC substitutions during gBGC.
• Found pervasive evidence of rapid compensatory evolution after gBGC episodes, driven by standing genetic variation.

Conclusions:

• gBGC significantly impacts amino acid sequence evolution.
• Compensatory evolution plays a crucial role in repairing gBGC-induced damage.
• Epistasis is key in protein adaptation, with beneficial mutations arising from various evolutionary processes.