Genetic variation and task specialization in the desert leaf-cutter ant, Acromyrmex versicolor

The genetic diversity in social insect colonies that is generated by multiple mating or multiple queens has been hypothesized to promote worker task specialization and therefore facilitate division of labour. However, few studies have actually examined the mechanisms by which genotype may influence individual worker behaviour. In this study, we dissect possible genetic effects on worker task performance in the desert leaf-cutter ant. We hypothesize that genotype could affect worker behaviour via (1) the rate of age-related task switching (age polyethism schedule), (2) individual task preference, and/or (3) task performance rates. To discriminate among these possible mechanisms, we generated composite colonies of workers from different genetic sources and followed the behaviour of individually marked workers over their lifetimes. We found significant differences among matrilines (offspring of different queens) in overall task performance. In particular, we found a negative covariance in likelihood of foraging versus tending fungus inside the nest. Workers of different matrilines also varied in the age of transition from inside the nest to foraging, but did not vary in task performance rates. Our results suggest that division of labour in this system is affected by genetic influences on individual task preference and age-related task choice, but not on variation in activity level.