Undertaking specialization in the desert leaf-cutter ant Acromyrmex versicolor

We investigated undertaking behaviour in the desert leaf-cutter ant to dete rmine whether colonies show undertaking specialization, how task specializa tion is regulated and the consequences of specialization on colony performa nce. Task specialization has been hypothesized to be a result of internal p hysiological or genetic factors that govern worker behaviour. On the other hand, it has been suggested that task specialization could be a result of s patial structuring of workers allowing only a subset to have the opportunit y to perform certain tasks. To test between these two hypotheses, we experi mentally introduced dead ants into laboratory colonies with individually ma rked workers, and recorded all encounters and undertaking behaviours. Worke rs demonstrated individual specialization, in that some workers removed the dead ant more frequently than expected from encounter rate. Although indiv idual workers differed in their opportunity to perform undertaking, this di d not account for the specialization. These results suggest that undertakin g specialization is governed by internal differences among workers. In addi tion, undertaking specialists removed corpses more successfully, and in the largest colony, more quickly, than nonspecialist workers, indicating that internally governed specialization is an important part of overall colony e fficiency. (C) 1999 The Association for the Study of Animal Behaviour.