Portrait of author

Hailin Pan:
Population genetics reveals the selection of honey bee aggression behaviour

Date: 11-12-2019    Supervisor: Guojie Zhang

Honey bees are famous eusocial insects with specialized reproduction and labour divisions. They are also important and primary pollinators and produce numerous values in agriculture. The honey bee is not only a classical model organism for investigating the evolution of eusociality but also a perfect biological subject for aggression behaviour analysis. This thesis mainly centred on honey bee aggression levels as well as the solitary alkali bee genome. The first two chapters focused on honey bee aggression level analysis. Chapter one described the re-sequencing of 90 individual honey bees contain three sub-groups (Africanized honey bee, European honey bee and gentle Africanized honey bee). Each sub-group was sequenced with 30 male individuals. Africanized honey bees show highly aggressive behaviour, while the other two display more gentle behaviour. By comparing genotype differences among these three sub-groups, we speculated that the gentle Africanized honey bee has undergone a soft selective sweep selection over an approximately 12-year period. Chapter two continued the study from chapter one. A total of 210 female gentle Africanized honey bee individuals from 10 colonies were collected. Each colony provided 10 foragers, 10 soldiers and the queen. The aggression levels of each colony were recorded during sample collection. We found that several loci had a significant correlation with colony aggression levels. The first two chapters provided a glimpse to understand the genetic mechanism of honey bee aggression levels. The last chapter presented a comparative genome analysis of an alkali bee, which is a basal Halictidae species. By low-coverage resequencing of 19 individuals, we identified 479 positively selected genes and recent population bottlenecks. Because the alkali bee is the basal solitary Halictidae species, these genomic data could be used as the ancestor states of sociality evolution and promote eusocial evolution research.