Genetic Effects on Rescue Behavior in a Social Insect with a Supergene

Abstract Many animals engage in rescue behavior. Rescue in social species is particularly interesting, because multiple individuals work together to coordinate rescue activities. This study investigates genetic effects on rescue behavior in the fire ant Solenopsis invicta. We determined if S. invicta workers who assisted in cooperative rescue of brood differed genetically from those who did not. We elicited rescue of brood in the lab by burying larvae in a sand-like substrate, imitating the potential result of a brood chamber collapse. We genotyped rescuers and non-rescuers at variable DNA microsatellite markers to understand the relationships among rescuers, non-rescuers, and the rescued larvae. We found significant genetic differentiation between rescuers and non-rescuers. These results suggest that genotype is a contributing factor in how social groups allocate individuals for rescue activity. Additionally, we genotyped individuals at a genetic marker linked to the S. invicta supergene, which dictates many aspects of social function. Overall, we did not find evidence for an effect of the supergene on rescue participation. Furthermore, genotyping of the buried larval targets enabled us to investigate nepotism and green-beard effects. However, we did not find evidence for either. Overall, our data provide evidence for an underlying genetic basis to an altruistic social behavior. Our results further our understanding of the genetic mechanisms underlying important group behaviors in societies.