Mating system and recombination affect molecular evolution in four Triticeae species

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Evolution

Background:

• Mating systems and recombination significantly impact genome organization and evolution.
• Reduced recombination and self-fertilization can decrease selection efficacy, affecting protein evolution and codon bias.
• Recombination also influences non-selective processes like GC-biased gene conversion (bGC).

Purpose of the Study:

• To investigate the effects of mating systems and recombination on molecular evolution in Triticeae species.
• To determine how GC content and selection efficacy are influenced by these factors.
• To explore the reasons for discrepancies between theoretical predictions and observed selection efficacy.

Main Methods:

• Comparative analysis of four Triticeae species: two outcrossers (Secale cereale, Aegilops speltoides) and two selfers (Triticum urartu, Triticum monococcum).
• Examination of GC content and selection efficacy in relation to mating systems and recombination rates.
• Investigation into potential mechanisms driving observed molecular evolutionary patterns.

Main Results:

• GC content is significantly affected by mating system and recombination, aligning with predictions for bGC.
• Selection efficacy shows only a weak response to mating system and recombination.
• Outcrossing species exhibit reduced selection efficacy, potentially due to a 'GC-induced' genetic load from high GC-favoring substitution rates.

Conclusions:

• Mating systems and recombination demonstrably shape genome evolution in Triticeae.
• GC-biased gene conversion plays a role in GC content variation.
• The 'GC-induced' genetic load in outcrossers offers a novel explanation for mating system evolution.