Genomic Architecture of Nestmate Recognition Cues in the Desert Ant

Nestmate recognition is the basis for cooperation within social insect colonies. Quantitative variation in cuticular hydrocarbons (CHCs) is used for nestmate recognition in ants and other social insects. To infer genetic effects on CHC variation, we tested for association between CHCs and polymorphic genetic loci to identify potential quantitative trait loci (QTL). 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 odor model, social interactions between nestmates, in which CHCs are transferred and mixed, are essential in creating a uniform colony CHC profile. Therefore, we carried out a second GWAS between the colonies and their Gestalt odor by averaging nestmate genotypes and comparing them to their averaged CHC amounts. Together, the two analyses identified 99 candidate QTLs associated with 18 out of 34 CHCs. Thirteen clusters of two to four QTLs located within 10 cM of each other were identified, seven of which contained QTLs from both analyses. We conclude that nestmate recognition cues are complex quantitative colony-level traits with a significant genetic component to their phenotypic variation and a highly polygenic architecture.