High numbers of unrelated reproductives in the Australian ‘higher’ termite Nasutitermes exitiosus (Blattodea: Termitidae)

Social insect colonies are among the most complex social organisations in nature, with reproductive and non-reproductive individuals co-ordinating to maintain the survival of the colony. Multiple reproductive schemes occur in social insects, from simple schemes with one founding reproductive pair, to more complex ones involving within-colony inbreeding and more than two unrelated reproductives. Colony breeding schemes and genetic structure remain understudied in termites, compared to the Hymenoptera. In this study, we performed the first genetic characterisation of the colony breeding structure of Nasutitermes exitiosus (Blattodea: Termitidae), an endemic Australian termite with a broad distribution across southern mainland Australia. We analysed the genetic structure of 60 N. exitiosus colonies from the Eastern part of its distribution, using microsatellites and mitochondrial sequence data. We found that most colonies were headed by one founding pair of reproductives, although some colonies exhibited a more complex breeding structure, including within-colony inbreeding and the presence of multiple unrelated reproductives. We found evidence for the presence of seven unrelated queens in one colony, to our knowledge, the highest number of unrelated queens yet found in a termite from the family Termitidae. We found some evidence for genetic isolation by distance, indicating that the species is a relatively poor disperser over long ranges.