Limits of vector calibration in the Australian desert ant, Melophorus bagoti
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Desert ants that forage solitarily continually update their position relative to the nest through path integration. This is accomplished by combining information from their celestial compass and pedometer. The path integration system can adapt when memories of previous inbound routes do not coincide with the outbound route, through vector calibration. Here, we test the speed and limit of vector calibration in the desert ant Melophorus bagoti by creating directional conflicts between the inbound and outbound routes (45°, 90°, 135°, 180°). The homeward vector appears to calibrate rapidly after training with shifts occurring after three foraging trips, yet the limit of the vector’s plasticity appears to be a maximum of 45°. At 45° conflicts, the vector calibrates the full 45°, suggesting dominance of the previous inbound memories over the outbound cues of the current trip. Yet at larger directional conflicts, vector shifts after training diminish, with foragers in the 90° and 135° conditions showing smaller intermediate shifts between the inbound memories and the current outbound vector. When the conflict is at its maximum (180°), foragers show no calibration, suggesting the outbound vector is dominant. Panorama exposure during training appears to aid foragers orienting to the true nest, but this also appears limited to about a 45° shift and does not improve with training.
KeywordsAnts Path integration Vector navigation Vector calibration Memory
This research was supported by a Grant from the Australian Research Council (DP150101172) and many thanks to the Centre of Appropriate Technology for access to the field site and nests. The authors declare no conflict of interests in association with this work.
Experiments conceived and designed: CAF. Data collection and analysis: CAF. Manuscript production and revision: CAF and KC.
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