Population viscosity promotes altruism under density-dependent dispersal

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Population genetics

Background:

• Population viscosity, a measure of relatedness in local populations, is a proposed mechanism for kin selection.
• While viscosity can promote altruism by increasing interactions among relatives, it can also inhibit altruism through intensified kin competition for resources.
• Previous models showed fixed dispersal probabilities negate viscosity's net effect on altruism.

Purpose of the Study:

• To investigate the role of density-dependent dispersal in the evolution of altruism under population viscosity.
• To determine if conditional dispersal can resolve the conflict between kin interaction and kin competition.

Main Methods:

• Analytical modeling of evolutionary game theory.
• Individual-based simulations to test theoretical predictions.
• Analysis of the relationship between dispersal rates and altruism levels under varying population densities.

Main Results:

• Conditional dispersal, where individuals adjust movement based on local density, favors altruism under population viscosity.
• Higher altruism levels correlate with increased dispersal rates, which alleviates kin competition.
• A negative correlation between overall dispersal and altruism is observed across populations or species.

Conclusions:

• Density-dependent dispersal is crucial for population viscosity to promote the evolution of altruism.
• Conditional dispersal strategies can overcome the inhibitory effects of kin competition, facilitating altruistic behaviors.
• This mechanism offers a broader explanation for altruism across diverse taxa, including those lacking kin recognition.