Intraindividual variability in behavior shapes fitness landscapes

Area of Science:

• Ecology
• Evolutionary Biology
• Behavioral Ecology
• Theoretical Ecology

Background:

• Intraindividual variability (IIV) in behavior is crucial for ecological dynamics but its evolutionary drivers are unclear.
• Understanding IIV is key to predicting population and community-level responses to environmental change.

Purpose of the Study:

• To investigate the impact of stochasticity on the evolution of intraindividual variability (IIV) in behavior.
• To determine how within-generation and between-generation stochasticity influence the maintenance and selection of IIV.

Main Methods:

• An individual-based model simulating prey behavior in response to predator encounters was developed.
• The model incorporated prey strategies defined by mean and standard deviation of hiding duration (IIV).
• Sources of stochasticity included random predator encounters (within-generation) and resource availability (between-generation).

Main Results:

• Between-generation stochasticity maintains high IIV in populations, despite a theoretical optimum of no IIV.
• The mean behavioral trait and IIV interact to influence fitness, leading to complex selection patterns.
• High IIV can be transiently selected for, even when the population evolves towards a strategy with no IIV.

Conclusions:

• Between-generation stochasticity is a significant factor in maintaining high levels of intraindividual variability in behavior.
• The interplay between mean traits and IIV complicates evolutionary trajectories, potentially favoring temporary increases in variability.
• These findings highlight the importance of considering environmental stochasticity when studying behavioral evolution.