Indirect genetic effects should make group size more evolvable than expected.

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Quantitative genetics

Background:

• Group size is a crucial trait influencing ecological and evolutionary dynamics.
• Understanding the genetic basis of group size is challenging as it is a social, not individual, phenotype.
• Existing models may underestimate the evolutionary potential of group size due to its complex genetic architecture.

Purpose of the Study:

• To propose a conceptual framework for modeling group size as a joint phenotype.
• To elucidate the role of indirect genetic effects in the evolution of group size.
• To predict the evolutionary trajectory and speed of group size changes.

Main Methods:

• Modeling group size as a joint phenotype influenced by multiple genomes.
• Incorporating indirect genetic effects into evolutionary models.
• Analyzing the direct and indirect genetic contributions to group size variance.

Main Results:

• Group size exhibits greater genetic variance than previously assumed.
• Indirect genetic effects contribute equally to direct genetic effects on group size.
• The correlation between direct and indirect genetic effects is maximized (1), accelerating evolutionary response.

Conclusions:

• Models accounting for indirect genetic effects are essential for understanding group size evolution.
• Group size is expected to evolve rapidly, showing swift increases and decreases.
• This framework provides new insights into the evolutionary dynamics of social traits.