The formation of the nestmate recognition template in ants and its effect on behavioural variation

• Applicant: Volker Nehring, Ph.D.
• Subject Area: Evolution, Anthropology ; Sensory and Behavioural Biology
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 428886296

• Final Report Year: 2024

Final Report Abstract

Our behaviour towards others depends on whether we recognise them, for example by their faces. We compare the perceived face with prototypes of faces stored in our memory: the templates. We studied recognition template formation in ants to understand what information is stored in the templates and how templates are formed. Ants recognize nestmates by their odours and attack non-nestmates. We found that ants can incorporate the odours of nonnestmates into their recognition template to more accurately discriminate between nestmates and non-nestmates. They seem to do so through associative learning, by associating the odour of the non-nestmates with the aggression these enemies exhibit. We then studied the molecular processes underlying nestmate recognition, in particular the expression of odorant receptor (OR) genes in the antenna. We found that overall gene expression between age groups and size morphs differed more in the antennae than in other tissues. Because ants progress through different tasks throughout their lives, this indicates that OR gene expression is optimised for the different tasks. We further investigated whether OR gene expression might also react to environmental changes, e.g. in the odours perceived. Generally, we found OR gene expression to be colony-specific, which might increase the sensitivity of the recognition system. When we altered the nestmate recognition odours that the ants perceived, the OR gene expression changed. These changes were so specific that ants from different colonies that were exposed to the same odour also became more similar in their OR profiles, so that the colony differences were lost. Our results show that there are processes in the neural periphery that support nestmate recognition, but at the same time associative learning mechanisms are also involved. Nestmate recognition is thus a complex cognitive process that involves multiple layers of the neural system.

Publications

• Associative learning of non-nestmate cues improves enemy recognition in ants. Current Biology, 35(2), 407-412.e3.
  Bey, Mélanie; Endermann, Rebecca; Raudies, Christina; Steinle, Jonas & Nehring, Volker