The genetical theory of multilevel selection

Area of Science:

• Evolutionary biology
• Theoretical ecology
• Population genetics

Background:

• The theory of multilevel selection (MLS) explains adaptation at multiple biological levels.
• Existing MLS frameworks struggle with defining group traits and fitness, especially in populations with complex class structures.
• Applications of MLS are limited in social insects due to their caste, age, and sex differentiation.

Purpose of the Study:

• To develop a genetical theory of multilevel selection (MLS) that resolves conceptual difficulties.
• To address the challenge of class structure within the framework of MLS.
• To clarify the relationship between individual contributions and group-level traits, including reproductive success.

Main Methods:

• Developing a genetical framework for multilevel selection.
• Decomposing group-level traits into individual contributions.
• Analyzing the conditions for meaningful group-level trait-fitness covariance in class-structured populations.

Main Results:

• A genetical approach allows for the decomposition of group traits, even emergent ones, into individual contributions.
• A novel problem is identified: group-level trait-fitness covariance may be impossible in class-structured groups.
• The constituents of a social group belonging to separate classes can prevent meaningful group-level fitness covariance.

Conclusions:

• A genetical theory of MLS offers a more robust framework for understanding selection across different levels.
• The presence of distinct classes within a group fundamentally challenges the group-oriented approach to MLS.
• Future research should consider the implications of class structure for evolutionary dynamics in social organisms.