Population size interacts with reproductive longevity to shape the germline mutation rate

Area of Science:

• Evolutionary biology
• Genetics
• Molecular biology

Background:

• Mutation rates exhibit vast variation across species, influenced by generation time and effective population size.
• Large effective population sizes may facilitate selection against deleterious mutator alleles affecting DNA repair or cell division.
• The relationship between mutation rate and DNA repair mechanisms is complex in multicellular organisms with long generation times.

Purpose of the Study:

• To investigate the relationship between generation time, germline mutation rates, and DNA repair mechanisms in multicellular species.
• To test the hypothesis that longer generation times amplify fitness consequences of DNA damage, driving selection for enhanced repair.

Main Methods:

• Comparative analysis of mutation rates across species with varying generation times.
• Examination of germline mutation accumulation during different developmental stages (prepuberty vs. reproductive cells).
• Correlation analysis between generation time and mutation rates in reproductive cells and somatic tissues.

Main Results:

• Germline mutation rates per generation are inversely correlated with generation time.
• Species with longer generation times exhibit more effective mechanisms for avoiding and repairing mutations in reproductive cells.
• Germline mutation accumulation during prepuberty shows a weak positive trend with increasing generation time.

Conclusions:

• Long generation times likely drive selection for robust DNA repair systems in reproductive cells to mitigate amplified mutation consequences.
• The findings suggest a trade-off between mutation accumulation over longer lifespans and the efficiency of germline mutation avoidance.
• Results align with observations of lower somatic mutation rates in long-lived species, indicating selection to limit lifetime mutation load.