Selection on female behaviour fluctuates with offspring environment

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Population genetics

Background:

• Temporal variation in selection is a proposed mechanism for maintaining genetic diversity.
• Fluctuating selection may explain consistent individual differences in behavior.

Purpose of the Study:

• To test if ecological changes lead to fluctuating selection, maintaining variation in female behavioral traits in North American red squirrels.
• To investigate the role of competition for territories in driving these selection fluctuations.

Main Methods:

• Analyzed linear selection gradients on female aggression and activity over several years.
• Assessed the impact of selection on juvenile overwinter survival and maternal fecundity.
• Incorporated uncertainty in behavioral measures to evaluate its effect on selection estimates.

Main Results:

• Selection gradients on female aggression and activity fluctuated annually, correlating with juvenile competition levels.
• Selection primarily influenced juvenile overwinter survival, with minimal effect on maternal fecundity.
• Accounting for behavioral measurement uncertainty did not alter the observed pattern of fluctuating selection.

Conclusions:

• Temporal fluctuations in natural selection, driven by ecological changes like competition, can maintain heritable variation in female behavior.
• This mechanism is crucial for preserving individual differences in behavior within wild populations.
• The findings support the role of fluctuating selection in evolutionary processes.