Effective purifying selection in ancient asexual oribatid mites.

Area of Science:

• Evolutionary biology
• Genetics
• Asexual reproduction

Background:

• Sexual reproduction is theorized to prevent mutational meltdown via effective selection.
• Species transitioning to asexuality often show deleterious mutation accumulation.
• The long-term viability of ancient asexual lineages remains debated.

Purpose of the Study:

• To investigate the effectiveness of purifying selection in ancient asexual oribatid mites.
• To compare mutation accumulation in asexual versus sexual oribatid mite lineages.
• To assess if asexual reproduction is an evolutionary dead end.

Main Methods:

• Comparative analysis of transcriptome data from asexual and sexual oribatid mite lineages.
• Quantification of deleterious nonsynonymous and synonymous mutations.
• Evaluation of purifying selection efficiency across different lineages.

Main Results:

• Ancient asexual oribatid mites exhibit reduced accumulation of deleterious mutations compared to sexual relatives.
• Purifying selection is found to be more effective in asexual lineages than in sexual ones.
• Evidence suggests large asexual populations can maintain selection efficacy.

Conclusions:

• Asexual reproduction does not necessarily lead to mutational meltdown in the long term.
• Effective purifying selection in large populations can sustain asexual lineages.
• Sex is not an absolute prerequisite for the long-term persistence of animal lineages.