Towards powerful experimental and statistical approaches to study intraindividual variability in labile traits

Area of Science:

• Behavioural ecology
• Quantitative genetics
• Animal behaviour

Background:

• Consistent individual differences in average behavior (personality) and environmental response (plasticity) are well-studied.
• Emerging research indicates individuals also differ in their residual intraindividual variability (rIIV), a measure of behavioral consistency.
• Quantifying rIIV is crucial for understanding trait variation in labile traits like behavior and physiology.

Purpose of the Study:

• To provide a model for quantifying rIIV in labile traits using activity rates in guppies (Poecilia reticulata).
• To extend existing statistical models to assess the covariance between individual mean behavior and their rIIV.
• To offer a standardized methodology for sampling design and data analysis in rIIV research.

Main Methods:

• Utilized a doubly hierarchical generalized linear model, extending previous work on rIIV quantification.
• Applied the model to activity rate data from guppies (Poecilia reticulata).
• Accounted for time-related changes in behavior during data analysis.

Main Results:

• Guppies exhibited substantial and consistent differences in rIIV after controlling for time effects.
• A significant negative covariance was found between individual mean activity levels and their rIIV.
• More active individuals tended to display lower rIIV, indicating greater behavioral consistency.

Conclusions:

• Individual differences in rIIV are a significant component of behavioral variation in labile traits.
• The developed methodology provides a robust framework for quantifying rIIV and its covariance with mean traits.
• Further research can generalize this model to explore covariances with other phenotypic variation aspects.