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Environmental quality predicts optimal egg size in the wild
Njal Rollinson1, Jeffrey A Hutchings
1Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H4R2, Canada. njal.rollinson@gmail.com
The American Naturalist
|June 20, 2013
Summary
Parents adjust offspring investment based on environmental quality. This study shows that Atlantic salmon (Salmo salar) require larger egg sizes in lower-quality streams for optimal fitness.
Area of Science:
- Ecology
- Evolutionary Biology
- Fisheries Science
Background:
- Parental investment theory balances offspring number and quality.
- Environmental conditions can alter the relationship between offspring investment and fitness.
Purpose of the Study:
- To empirically test if optimal parental investment increases as environmental quality decreases.
- To investigate the influence of environmental factors on the optimal egg size in Atlantic salmon.
Main Methods:
- Released over 30,000 juvenile Atlantic salmon into eight distinct stream environments.
- Monitored juvenile growth and survival.
- Estimated the relationship between egg size (investment) and offspring fitness in each stream.
Main Results:
- Optimal egg size was larger in lower-quality stream environments.
- Stream habitat quality, specifically gravel size and sunlight, predicted optimal egg size.
- Juveniles in subsections with larger gravel and more sunlight exhibited faster growth.
Conclusions:
- Environmental quality significantly modifies the optimal level of parental investment.
- This study provides empirical evidence that higher investment per offspring is favored in poorer environments for Atlantic salmon.
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