Egg Size Scales Negatively With System Size in a Periodic Fish Species.

Area of Science:

• Ecology
• Evolutionary Biology
• Ichthyology

Background:

• Optimal egg size theory posits a trade-off between fecundity and offspring investment, influenced by environmental conditions.
• Interspecific studies indicate marine fish produce smaller eggs than freshwater fish, suggesting a link between system size and egg size.

Purpose of the Study:

• To investigate intraspecific variation in egg size within yellow perch (Perca flavescens) populations across a range of lake sizes.
• To determine if yellow perch exhibit a similar pattern of egg size variation as observed in interspecific studies, with smaller eggs in larger systems.

Main Methods:

• Collected yellow perch egg samples from 12 populations across systems varying from 37 to over 5 million hectares.
• Analyzed egg diameter in relation to maternal total length and system surface area.
• Accounted for maternal size effects to isolate the impact of lake size on egg size.

Main Results:

• Egg diameter significantly increased with maternal total length in most populations studied.
• A significant interaction revealed that females in larger lakes produced smaller eggs than those in smaller lakes, particularly among larger females.
• This pattern aligns with interspecific comparisons between marine and freshwater fishes.

Conclusions:

• Intraspecific egg size variation in yellow perch supports optimal egg size theory, demonstrating that maternal investment is context-dependent.
• Environmental factors, such as resource acquisition and competition in different-sized lakes, influence egg size.
• This study provides a single-species, within-species validation of broad ecological patterns in reproductive strategies.