Sex-specific selection under environmental stress in seed beetles.

Area of Science:

• Evolutionary biology
• Ecology
• Genetics

Background:

• Sexual selection, often male-biased, can accelerate adaptation by purging genetic load.
• The ecological sensitivity of sex-specific selection remains under-explored.
• Environmental factors can significantly influence evolutionary trajectories.

Purpose of the Study:

• To investigate the ecological sensitivity of male-biased sexual selection.
• To test theoretical predictions of sex-specific selection strengths and genotype-by-environment interactions.
• To understand how environmental stress impacts natural and sexual selection dynamics.

Main Methods:

• Theoretical predictions of sex-specific selection and environmental sensitivities were generated.
• Seed beetles were subjected to manipulated larval host plant and rearing temperature.
• Sex-specific fitness components, genotype-by-environment interactions, and selection strength (variance in fitness) were measured across life stages.

Main Results:

• Fitness variance increased with stress, being higher in males for adult reproductive success but similar for juvenile survival.
• Genetic variance in fitness increased under severe stress, while heritability decreased, especially in males.
• Genotype-by-environment interactions were common, sex-specific, and stage-specific.

Conclusions:

• Environmental stress alters the relative strengths of natural and sexual selection.
• Stress impacts genetic variance and heritability, with significant implications for male adaptation.
• New environments can change selection dynamics between sexes, influencing adaptation rates in sexual populations.