Diversity in identity: behavioral flexibility, dominance, and age polyethism in a clonal ant

Abstract

In many species of social insects, division of non-reproductive labor is to some extent affected by age, in that younger individuals engage in activities in the nest, whereas older individuals forage. While the link between age and task is less robust than originally thought, the transition from nursing to foraging is associated with large changes in gene expression, neuroanatomy, and physiology and therefore seems largely irreversible. Here, we investigate division of labor in the thelytokous ant Platythyrea punctata. Since it forms clonal colonies, it is an ideal model to investigate the behavioral flexibility of individuals and the proximate mechanisms underlying division of labor, while avoiding confounding factors, such as variation in genotype or morphology. We found that nurses and foragers of P. punctata differ in residual life span, fat content, fecundity, and the propensity to engage in dominance interactions. However, age-based division of labor appears to be flexible: foragers can revert to nursing and egg laying, even though they appear less fecund than original nurse workers. Interestingly, the transition from foraging to nursing seemed to slow down aging and senescence.

Appendices

Appendix 1

Table 1 Ethogram of P. punctata

Appendix 2

Fig. 5

Mean location score (±IC₉₅) for callow workers from 3 different colonies (PR9 = 8 callows, PR25 = 8 callows, and PR42 = 7 callows, one callow died during the first week of observation). Each ant was observed three times per day and 5 days per week during 6 weeks. At each observation, the ant’s location (inside = 0, nest entrance = 1 or outside the nest = 2) was scored. For clarity, only IC₉₅ of colony PR42 are represented on the figure