Causes And Consequences Of Eusocial Genome Evolution In The Small Carpenter Bee C. Calcarata And The Honey Bee A. Mellifera

Abstract

Bees provide excellent systems for understanding how social behaviour evolves and how it influences the genome, a central question within sociobiological research. Advances in genomic technologies now enable investigation of the evolutionary and molecular mechanisms underlying social complexity. I use genomic and population genetic approaches to investigate the mechanisms that contribute to the emergence of social behaviour and the genomic consequences of advanced eusociality in bees. I first review advances in bee genomics, highlighting how genome sequencing, transcriptomics, and other tools have improved our understanding of bee evolution and behaviour. Then, I suggest that combining molecular and genomic approaches provides a framework for identifying genes and molecular pathways associated with eusocial traits. Using the facultatively social Ceratina calcarata, I investigate genomic patterns linked to early stages of social evolution. Comparisons between social and subsocial colonies show that loci with high genetic differentiation are often located in or near regulatory regions. Comparisons with Ceratina strenua also identify genes under positive selection, particularly in genes involved in regulation and metabolism. Finally, I examine the genomic consequences of longevity in terms of changes in mutation and recombination rate in the advanced eusociality in Apis mellifera. Mutations are more likely to occur in regions with higher recombination and are less common in constrained genomic regions, suggesting that recombination and purifying selection shape patterns of mutation in the honey bee genome. Together, this work demonstrates how genomic approaches can uncover the origins of social behaviour and how eusocial life histories influence genome evolution in bees.