Molecular Evolution of the Brain Transcription Regulatory Network Affecting Worker Behaviour of Honey Bees (Apis Mellifera)

The brain transcription regulatory network drives the behavioural states of honey bee workers. It is paradoxical that labile behaviour is guided by a network of evolutionary conserved pleiotropic transcription factors. So how does adaptive change in behaviour arise? I used a population genomics approach to estimate the strength of selection on coding and cis-regulatory mutations of transcription factors and their target genes in the honey bee brain transcription regulatory network. I found that replacement mutations in highly connected transcription factors and target genes experience significantly stronger negative selection relative to weakly connected transcription factors and targets. Interestingly, connectedness and network structure had minimal influence on the strength of selection on putative regulatory sequences for both transcription factors and their targets. This study suggests that adaptive evolution of complex behaviour can arise because of positive selection on protein-coding mutations in peripheral genes, and on regulatory sequence mutations in both transcription factors and their targets throughout the network.