No abstract

Tandem running is a primitive recruitment method employed by many ant genera. This study characterizes this behaviour during the recruitment of colony mates to a new nest in an Indian ant Diacamma indicum. Tandem leaders who have knowledge of the new nest lead a single follower at a time, to the destination by maintaining physical contact. In order to characterize tandem running, we captured and analysed 621 invitations, 217 paths and 226 termination events. Remarkably, not a single colony member was lost. While invitations were stereotypic in behaviour, termination was not. Analysis of speed revealed that the average transport speed was 4.2 cm s−1. Coupled adult-brood transport was slower than other transports but was more efficient than individual trips. Comparing tandem running with other popular recruitment methods in ants allows us to postulate that even though tandem running is primitive it is probably just another means to achieve the same end.

SUPPLEMENTARY MATERIALFig. S1. -Maps showing subset of paths followed by transporters during colony relocation for six initiation-destination pairs totalling 105 transport events (N1 = 10, N2 = 15, N3 = 9, N4 = 34, N5 = 11 and N6 = 26), across five Diacamma indicum colonies. All relocations were conducted in theirnatural habitat and grassy patches in the experimental area have been marked green. The white disk represents the old nest (9 cm diameter); a 10 cm region extending from the nest exterior is represented using a dotted circle. Experiment with DI 607 yielded more than eight tracks for two of the target sites and hence both have been included. Note that all maps have been rotated so that the target nests fall directly to the right on the horizontal axis through the old nest.

No abstract

Decisions regarding spatial and temporal choices pertaining to a wide range of activities such as mating, feeding and resting are necessary for all organisms. Social species encounter another level of complexity, wherein inputs from multiple individuals have to be consolidated to yield a consensus. One platform on which decision making can be examined is the relocation of animal societies. Relocation is the process by which organisms move from their old dwelling to a new nest along with all the inhabitants. This exposes them to the elements and thus impacts their survival and reproduction. Diacamma indicum, the model system for our experiments is a ponerine ant that uses tandem running for colony relocation. In the present study an artificial manipulation was performed to cause a shift in the target nest. The flexibility of the relocation process and, more specifically, the response of tandem leaders to a changed target were studied. A majority of these leaders (N=262) not only re-evaluated and adapted to the change, but did so with negligible error (1.65%). This enabled colonies (N=10) to reunite at the target nest in every case. The only cost to this flexible decision making was paid in terms of additional time. Although considered to be a primitive method of recruitment, we reveal that tandem running allows D. indicum leaders to incorporate assessment of the available options at every step. This inherent flexibility in decision making would be a good strategy for organisms that need to function with incomplete information or inhabit environments that change frequently.