Learning genes identified in comparative brain transcriptome analysis of scouting and tandem-running in Temnothorax ants
Marah Stoldt, Marah Stoldt , Austin Alleman , Barbara Feldmeyer , Susanne Foitzik
Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany; Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany ; Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany ; Senckenberg Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany ; Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
Behaviour is a phenotypic plastic trait, which can change quickly both in response to ecological factors and during evolution. Gene expression analyses allow identifying genes linked to behaviours and if used in a comparative context to study whether the same genes are associated with behaviours of interest between species. Tandem-running is a recruitment behaviour exhibited by ants of different taxa and is used in different contexts. Tandem-leading was described as a form of teaching, leading to the expectation that tandem-followers should overexpress genes connected to spatial learning. However, also scouts which explore the surroundings for food, nest sites or host colonies, need to learn spatial locations. Here, we investigate gene expression in the brains of scouts, tandem-leaders and -followers of two species, Temnothorax longispinosus and its congener T. americanus. Whereas T. longispinosus workers were sampled during nest relocations, workers of the slavemaking ant T. americanus were taken during slave raid recruitment. We identified candidate genes overexpressed in the brain of workers exhibiting the three different behaviours. Moreover in both species, leaders showed the most overlap with scouts and followers, which can be explained by the fact that they were either scouts or followers before. We found interesting candidate genes in both species, which are associated with learning and memory formation in honey bees and other insects. For example scouts upregulated Glutamate-, Tyramine- or Allastostatin receptors. Surprisingly, none of the differentially expressed genes were the same between the two species. However, we found some overlapping pathways as well as GO terms with similar functions, providing support for the looser genetic toolkit hypothesis, which suggests conserved functions and pathways rather than genes.