When Do Individuals Maximize Their Inclusive Fitness?

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Population Genetics

Background:

• Adaptation is commonly viewed as individuals maximizing inclusive fitness.
• The gene-centered perspective offers an alternative framework for adaptation.
• Existing theories often overlook class structure in populations.

Purpose of the Study:

• To unify and extend the understanding of adaptation in class-structured populations.
• To investigate the conditions under which individuals maximize inclusive fitness.
• To reconcile actor-centered and gene-centered perspectives on adaptation.

Main Methods:

• Developed a theoretical framework for class-structured populations.
• Analyzed conditions for uninvadable population states.
• Investigated the role of demographic and genetic contexts.
• Examined the implications of weak selection.

Main Results:

• Class-specific inclusive fitness maximization occurs in uninvadable population states.
• Individual inclusive fitness maximization is generally not autonomous due to context dependence.
• Under weak selection, individuals appear to maximize their own inclusive fitness as a first-order approximation.

Conclusions:

• The study provides a genuine actor-centered perspective on adaptation in structured populations.
• It formally justifies the individual-centered view of adaptation under specific conditions (weak selection).
• Highlights the limitations of viewing individuals as entirely autonomous fitness maximizers.