Optimal reproductive-skew models fail to predict aggression in wasps

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Optimal-skew models (OSMs) propose that reproductive division in cooperative breeding is linked to dominance contests and aggression.
• Polistine paper wasps are a key model for testing OSMs, with previous studies interpreting aggression as evidence supporting these models.
• Existing research often measures aggression as a rate, potentially conflating hostility with individual activity levels.

Purpose of the Study:

• To re-evaluate the support for Optimal-Skew Models (OSMs) in polistine paper wasps.
• To investigate whether observed aggression patterns accurately reflect reproductive skew or are influenced by individual activity states.
• To test the assumption that aggression directly correlates with reproductive partitioning in cooperative breeding systems.

Main Methods:

• Replication of a field manipulation previously used to support OSMs in paper wasps.
• Detailed analysis of individual activity patterns alongside behavioral observations.
• Statistical control for individual activity states when assessing aggression and reproductive skew.

Main Results:

• Controlling for individual activity states led to fundamentally different conclusions compared to previous studies.
• Observed behaviors previously labeled as 'aggression' showed a weak link to establishing or maintaining reproductive skew.
• The findings challenge the direct interpretation of aggression as a sole indicator of reproductive partitioning in paper wasps.

Conclusions:

• Aggression in paper wasps may not function as predicted by Optimal-Skew Models for regulating reproductive skew.
• Tests of OSMs using non-reproductive behaviors like aggression require empirical validation of the link to reproductive partitioning.
• Future research should carefully account for activity states when studying the role of behavior in cooperative breeding systems.