Measuring viability selection from prospective cohort mortality studies: A case study in maritime pine

Area of Science:

• Evolutionary Biology
• Population Genetics
• Genomics

Background:

• Stage-specific selection shapes adaptive potential across life cycles.
• Investigating selective mortality is crucial for understanding evolutionary processes.
• Existing methods often require individual tracking, limiting application in large cohorts.

Purpose of the Study:

• To develop and evaluate a neutrality test and Bayesian method for inferring stage-specific viability selection coefficients.
• To provide a method suitable for large natural or experimental cohorts where individual tracking is unfeasible.
• To analyze viability selection in early recruitment stages of maritime pine (Pinus pinaster).

Main Methods:

• Utilized sequential random genotypic samples from a longitudinal cohort mortality study within a generation.
• Applied a neutrality test and Bayesian inference to estimate stage-specific viability selection coefficients.
• Analyzed temporal genotypic frequency changes at 384 candidate-gene SNP loci in maritime pine seedlings.

Main Results:

• Numerical simulations showed the method can discriminate loci under strong viability selection and provide accurate coefficient estimates with large samples.
• The method's inference is compromised by sampling noise under weak selection.
• Five loci with allele frequency changes larger than expected were detected in maritime pine seedlings, suggesting roles in early survival.

Conclusions:

• The proposed statistical and sampling methods enable genomic scans of contemporary selection on specific life stages.
• The findings highlight the importance of stage-specific selection in natural populations.
• The study provides a powerful tool for evolutionary and ecological research.