The adaptive significance of social information in tandem-running ants

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Social learning is widespread in nature and plays an important role in the acquisition of locally adaptive behaviours in many animals. Yet, it is still poorly understood why and when social learning is more beneficial than individual learning. While social learning can provide a low-cost, low-risk strategy to acquire information, it is also prone to acquiring outdated, unreliable and even maladaptive information. In a recent simulation study published in Science, Rendell et al. (2010) tested the success of different learning strategies in varying environments and found that social learning leads to greater rewards than individual learning in almost all ecological situations. These results challenge the widespread believe that animals should follow mixed strategies and they contradict the assumption that a pitfall of social learning is the acquisition of low-quality information. However, the authors did not provide any empirical data to support their conclusions and it remains unknown whether social learning leads to the acquisition of more successful behaviour. So far, progress has been hampered by the difficulty to collect and interpret empirical data. Communication in social insects has been studied since nearly a century, but only recently have insights been viewed in the light of social learning theory. Many ant species use a form of recruitment called tandem running, whereby an informed individual guides an uninformed nestmate to a resource. Tandem running is currently the only known example of teaching in non-mammals and represents a promising behaviour to study the benefits of social information at both individual and colony level. This project proposes to use tandem running in ants to test general predictions of social learning theory, in particular the prediction from the Rendell et al. (2010) model that social learning leads to better rewards than individual learning. We plan to explore these questions in the laboratory and the field using the common temperate species Temnothorax nylanderi and the Neotropical species Neoponera verenae. More specifically, we aim to answer the following 5 questions: (i) How frequent are social learning, individual learning and personal information use in foragers of these two species? (ii) How does social learning affect the success of a forager and how does this depend on the abundance and variability of food resources? (iii) How important is social learning for colony foraging success? (iv) Do individuals frequently switch between different information-use strategies or are information-use strategies part of a worker personality? (v) Are intra-colonial differences in information-use linked to variation in worker morphology? Answering these questions will improve our understanding of the adaptive value of social information in tandem running ants and help us to better understand the circumstances the favour the evolution of communication about resources in social insects.