Direct and indirect phenotypic effects on sociability indicate potential to evolve.

Area of Science:

• Behavioral Ecology
• Evolutionary Genetics
• Animal Behavior

Background:

• Group size significantly impacts organismal fitness and life history.
• Sociability, the tendency to associate with others, is theoretically influenced by direct and indirect genetic effects.
• Estimating these genetic influences on social behavior is challenging.

Purpose of the Study:

• To estimate phenotypic parameters for sociability in cockroaches, specifically repeatability (R) and repeatable influence (RI).
• To quantify the interaction coefficient (Ψ), reflecting partner trait influence on focal individual phenotype.
• To investigate the role of direct and indirect genetic effects and partner body mass on sociability.

Main Methods:

• Utilized a laboratory population of the cockroach Blaptica dubia.
• Estimated repeatability (R) of sociability over a 3-week period.
• Measured repeatable influence (RI) and the interaction coefficient (Ψ) in dyadic trials and social networks.

Main Results:

• Sociability showed moderate repeatability (R = 0.080) and marginal repeatable influence from partners (RI = 0.053).
• The interaction coefficient (Ψ) was non-zero and sex-specific: males preferred larger partners (Ψmale = -0.129), females preferred smaller partners (Ψfemale = 0.071).
• Individual sociability was consistent across different social contexts.

Conclusions:

• Direct and indirect genetic effects appear to have limited influence on cockroach sociability.
• Heritable effects of partner body mass may be a significant driver of social behavior evolution.
• Sex-specific interaction coefficients suggest potential for sexual conflict and the evolution of sexual dimorphism in social behavior.