How does egg size relate to body size in butterflies?

Area of Science:

• Evolutionary biology
• Developmental biology
• Entomology

Background:

• Arthropod egg size is crucial for evolution and ecology, but its determinants are poorly understood.
• Previous studies suggested butterfly egg size correlates with adult size, implying morphological constraints.
• Intra-populational variation in egg size exists, necessitating further investigation into its drivers.

Purpose of the Study:

• To investigate the factors influencing egg size variation within butterfly populations.
• To determine if female body size constrains egg size evolution in butterflies.
• To explore the relationship between egg size, hatchling size, and development time.

Main Methods:

• Utilized laboratory populations of the tropical butterfly Bicyclus anynana.
• Analyzed intra-populational variation in egg size.
• Correlated egg size with female body size and development time.
• Examined egg size in populations subjected to artificial selection for body size.

Main Results:

• Larger eggs resulted in larger hatchlings, with significant intra-populational variation in egg size.
• The correlation between female body size and egg size was weak, explaining only 1% of the variation.
• Development time was a slightly better predictor of egg size than female size.
• Populations artificially selected for body size showed correlated responses in egg size.

Conclusions:

• Female body size does not appear to impose a significant constraint on egg size evolution within Bicyclus anynana populations.
• Correlations between body size and egg size may emerge under specific conditions, such as artificial selection, indicating an emergent property.
• Understanding the drivers of egg size variation is essential for comprehending evolutionary and ecological dynamics in insects.