Nutrients from salmon parents alter selection pressures on their offspring

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Organisms modify environments, but feedback on evolution is poorly understood in wild populations.
• Parental nutrient contributions can influence offspring ecology and evolution.

Purpose of the Study:

• To investigate how nutrient pulses from decomposing Atlantic salmon (Salmo salar) parents affect offspring evolutionary trajectories.
• To determine the impact of parental nutrient input on selection pressures, phenotypic diversity, and genetic diversity in wild salmon populations.

Main Methods:

• Field study comparing salmon offspring in streams with and without parental carcasses (nutrient input).
• Measured survival rates, egg size, juvenile metabolic rates, and family diversity.
• Analyzed phenotypic divergence and selection intensities.

Main Results:

• A survival advantage for larger eggs and faster juvenile metabolic rates was observed in streams lacking salmon carcasses.
• This advantage was absent in streams with parental nutrient input.
• Significant phenotypic divergence in egg size and metabolic rate occurred between stream types.
• Lower parental nutrient levels resulted in stronger selection and reduced family survival.

Conclusions:

• Parent-derived nutrients significantly alter selection pressures on offspring.
• Nutrient subsidies from parents can dampen eco-evolutionary feedbacks in wild populations.
• Provides experimental evidence for environmental modification influencing evolutionary trajectories.