Vector-based and landmark-guided navigation in desert ants of the same species inhabiting landmark-free and landmark-rich environments

Summary The central Australian desert ant Melophorus bagoti lives in a visually cluttered semi-arid habitat dotted with grass tussocks, bushes and trees. Previously, Bühlmann et al. (Bühlmann et al., 2011) have shown that this species has a higher propensity to switch from vector-based navigation to landmark-guided navigation, compared with the North African desert ant Cataglyphis fortis, which usually inhabits a visually bare habitat. Here we ask whether different colonies of M. bagoti, inhabiting more and less cluttered habitats, also show a similar difference. We compared ants from typically cluttered habitats with ants from an exceptional nest located on a open field largely devoid of vegetation. Ants from both kinds of nests were trained to forage from a feeder and were then displaced to a distant test site on the open field. Under these conditions, ants from cluttered habitats switched more readily from vector-based navigation to landmark-guided navigation than ants from the open field. Thus, intraspecific differences due to the experience of particular landmarks encountered en route, or of particular habitats, ride on top of previously found interspecific, inherited differences due to the evolutionary history of living in particular habitats (Bühlmann et al., 2011).