Genomic architecture of nestmate recognition cues in the desert ant

Nestmate recognition is the basis for cooperation within social insect colonies. Quantitative variation in cuticle hydrocarbons (CHCs) is used for nestmate recognition in ants and other social insects. We carried out a Genome Wide Association Study (GWAS) of CHCs in the desert ant Cataglyphis niger by sampling 47 colonies, fully sequencing six workers from each colony, and measuring the relative amounts of their CHCs. Under the Gestalt colony odour model, social interactions between nestmates, in which CHCs are being transferred and mixed, are essential in creating a uniform colony CHC profile. Therefore, we carried out a second GWAS between the colonies and their uniform Gestalt odour by averaging nestmate genotypes and comparing them to their averaged CHC amounts. Our results are in line with the Gestalt model. Together, the two analyses identified 99 candidate QTLs associated with 18 of the CHCs. Thirteen clusters of two to four QTLs located within 10cM from each other were identified, seven of which contained QTLs from both analyses. We conclude that nestmate recognition cues are a complex quantitative colony-level trait with a significant genetic component to their phenotypic variation and a highly polygenic architecture.