An insect society can serve as a hub of transmission for pathogens, commensals, and mutualists (symbionts), but transmission within a colony occurs between close relatives. If this consanguineous transmission is much more prevalent than between-colony transmission, selection may favor more benevolent symbiont strains in social hosts in comparison to solitary hosts, because high consanguineous transmission may couple the fitness of the symbiont to that of the host colony. To test this hypothesis, genetic covariances between social and solitary sweat bee hosts and their nematode symbionts are being measured to represent effective transmission. Effective transmission is a measure of within- versus between-colony transmission, and therefore provides a means to measure the coupling of host and symbiont fitnesses. Laboratory colonies of social and solitary hosts either with or without symbionts will be used to measure the impacts of infection on host fitness. This research will also determine if genetic covariances can predict the impact of a symbiont on its host.
This project will involve the training undergraduates, including students from underrepresented groups. Additionally, this research has direct relevance to the understanding of disease dynamics in social systems of all kinds, from humans to slime molds.
