Population Genomic Approaches to Understanding the Genetics and Evolution of Social Insects
Harpur, Brock Alexander
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Eusocial animals are comprised of distinct and specialized individuals that carry out specific tasks within colonies. Despite decades of research on eusocial insects (e.g. bees, wasps, termites, and ants), we lack knowledge on the genetics underlying social traits, and how the genomes of eusocial insects evolved over relevant timescales. I pioneered the use of next generation sequencing of populations of eusocial insects population genomics to characterize genomic regions that influence fitness and to study the genetics of two social traits. I first identified which genes have evidence of adaptive evolution within two genera: the primitively eusocial bumble bees and the highly eusocial honey bees (Chapters 2 and 3). Using a comparative approach, I found clear differences in which genes contribute to fitness within each lineage and in the caste-specific contributions to fitness at these two stages of social evolution. I then discovered the genes underpinning social immunity (Chapter 4) and colony defense (Chapters 5 and 6) in honey bees. I uncovered strong support that variation in social immunity arises through differential regulation of highly conserved neuronal developmental genes and that these genes have historical patterns of adaptive evolution. After creating a large genomic data set for a highly defensive honey bee population (Chapter 5), I discovered that variation in colony defense is underpinned by differences in inheritance of ancestral alleles. Finally, using population genomic data on honey bees, I tested the utility of a single nucleotide polymorphism assay to study the ancestry of Canadian honey bees, creating a powerful tool for securing the importation of honey bees into Canada (Chapter 7). My research highlights the importance of genomic data for understanding the genetics and evolution of social traits.