Response of Leaders to Moving Targets in Ant Relocation

Anoop, K (2013) Response of Leaders to Moving Targets in Ant Relocation. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS Dissertation of Anoop K) Anoop_K-08MS55-MSThesis.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

Unlike solitary organisms eusocial insects possess a decentralized system; hence the decision-making process often involves inputs from multiple individuals, making the process more complex. One context where decision making is important would be the choice of a target nest among multiple options, when the current one becomes inhospitable. Unlike bees and wasps, relocation in ants involves transfer of brood of different stages which are not only vulnerable, but also represent a substantial segment of the colony‟s resource investment (Hőlldobler & Wilson 1990; Visscher 2007) which would make the whole process even more complicated. Diacamma indicum, the model system for our experiments is a queenless ponerine ant found in the south and east of India and in Sri Lanka. It uses tandem running for colony relocation (Kaur et al. 2012; Sumana & Sona 2012). A tandem run involves the transfer of one ant (follower) from one site to another by a different ant (leader). In the present study an artificial manipulation of the nest qualities was performed, after relocation had started, so as to cause a shift in the target nest. Then we attempt to understand the overall flexibility of the relocation process and specifically the response of leaders to moving targets in ant relocation. D. indicum exhibited complete flexibility in its response to a shift in the target nest without a significant increase in the relocation effort. However the time taken for the relocation process was higher. A fifth of the colony members actively participated in the relocation process as leaders and a significant majority of these leaders could assess the environment on a continuous basis and respond effectively to the change in the nest qualities. The change in the nest qualities did not affect the speed or the efficiency of the relocation process carried out by these individuals, however, this response to the change in nest qualities involved a delay and this led to an overall delay in the relocation process. Preliminary studies of the relocation process also suggest that the choice of a target nest may not depend on quorum sensing but on the decisions made by a few key individuals who are not only active but also accurate. Though a primitive method, D. indicum uses tandem running with little error and incorporates evaluation of their choices at every step to maintain flexibility within the relocation process. This inherent flexibility in decision making process will allow colonies to adapt better to changing environments.

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