Quantifying evolutionary potential of marine fish larvae: heritability, selection, and evolutionary constraints

Area of Science:

• Marine biology
• Evolutionary ecology
• Quantitative genetics

Background:

• Intense larval mortality in marine fish offers selection opportunities.
• Limited knowledge exists on the evolutionary potential of larval traits.

Purpose of the Study:

• Estimate quantitative genetic parameters for larval size and swimming performance in bicolor damselfish (Stegastes partitus).
• Examine selection on larval size using field and experimental data.
• Reconstruct adaptive landscapes for larval traits.

Main Methods:

• Combined field demographic studies and manipulative experiments.
• Estimated quantitative genetic parameters (heritability).
• Synthesized published estimates of selective mortality.
• Applied the Lande-Arnold framework to reconstruct adaptive landscapes.

Main Results:

• Demonstrated strong viability selection favoring larger larvae.
• Found moderate heritability (h(2) = 0.29) for larval size.
• Identified reproductive selection favoring mothers producing more, smaller offspring.
• Indicated size-number trade-offs may constrain long-term evolutionary responses.

Conclusions:

• Phenotypic variation in larval size is crucial for population dynamics.
• Larval survival and recruitment are significantly affected by larval size variation.
• Evolutionary responses of larval traits are likely balanced by maternal reproductive strategies.