Exploring task allocation within ant cofoundress associations

Cofoundresses of the desert leaf-cutter ant Acromyrmex versicolor exhibit above-ground surface excavation specialization and foraging specialization prior to eclosion of the first adult workers; the foundress displaying the former task specialization assumes the latter specialization significantly more often than expected randomly. Determination of both task specializations is not correlated with relative cofoundress mass; nor is there evidence of overt or ritualized aggression. Excavation specialists retain their task specialization when paired with "non-excavating" foundresses from other nests, but both types of foundress can assume the complementary role if paired with an individual of their original task specialization. There is no evidence of a "war of attrition" among cofoundresses at colony initiation; rather, our data seem consistent with a "coordination mechanism" within economic game theory where roles are assigned through differentially-experienced, arbitrary events beyond individual control. When the conditions of coordination are removed, however, cofoundresses exhibit behaviour consistent with a war of attrition. Coordination and a war of attrition need not be conflicting explanations but are rather complementary, contingent on divergent conditions.