Abstract

Global decline among bumblebees shows strong evidence of phylogenetic structure, with the subgenus Pyrobombus over-represented among stable/range-expanding species. Based on this striking pattern, a hypothesis was drawn up suggesting that Pyrobombus species have acquired advantageous traits that enhance their survivability and dispersal compared to other subgenera. This hypothesis explores the possibility that these advantageous traits were acquired via the evolutionary process and are detectable as genomic signatures unique to the subgenus when compared with other subgenera.Twenty-four bumblebee species, representing all 15 subgenera and including 6 Pyrobombus species, were compared. The first study investigated genomic inversions and duplications. Pyrobombus was characterized by a set of 59 inversions present in four or more of its species but absent from all other subgenera. In the second study, gene presence absence variation (PAVs) was analysed. Pyrobombus-specific PAVs (present in one or more Pyrobombus species but absent from all other subgenera), were more strongly associated with GTPase signalling pathways and certain innate immunity pathways compared to genes present only in non-Pyrobombus species. The third study compared gene family expansions/losses. It detected a faster rate of gene family evolution in Pyrobombus, as well as a higher number of gene family expansions than most other species. The fourth study investigated positive selection, detecting a higher number of genes evidencing positive selection in Pyrobombus compared to other lineages, which were enriched for small molecule metabolism functions. In the final study, the first whole genome resources were generated for Bombus haematurus, a range-expanding Pyrobombus species that previously lacked them. This study generated a draft genome assembly for the species and through interrogation of the genome detecting a strikingly low nucleotide diversity compared to other bumblebees, as well as signatures of directional selection in developmental biology genes.

Awarding Institution(s)

University of Plymouth

Supervisor

Mairi Knight, Andrew Bourke, Jon Ellis, Wilfried Haerty, Vanessa Huml

Keywords

Genomics, Bioinformatics, phylogenetic signal

Document Type

Thesis

Publication Date

2026

Embargo Period

2026-01-19

Deposit Date

January 2026

Additional Links

https://doi.org/10.24382/8ky0-n281

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Recommended Citation

Hasan, S. (2026) Hard-wired for success? Unravelling genomic signatures in pollinators. Thesis. University of Plymouth. Available at: https://doi.org/10.24382/8ky0-n281

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