Year

2023

Degree Name

Bachelor of Conservation Biology (Honours)(Dean’s Scholar)

Department

School of Earth, Atmospheric and Life Sciences

Advisor(s)

Bethany Hoye

Abstract

Like many organisms, bacteria constantly face selective pressures that act on particular traits. However, they are also not passive actors in an evolutionary system. Host-switching events allow bacteria to expand their host range and accumulate adaptations specific to these hosts. Despite its recognition as containing many pathogens of concern, the Klebsiella genus is chronically understudied in wildlife. As such, knowledge of its capacity for host switching and the diversity of what is present in wildlife is largely unknown. This thesis aimed to complement significantly existing Klebsiella work in wildlife using an urban wildlife species, the Australian silver gull. Using the silver gull as a model, the diversity of Klebsiella in wildlife was quantified, as was the coexistence and persistence of Klebsiella lineages and their resistance, virulence and mobile cargo. Placing these in the context of host range allowed for analysis of how host range, and by extension, host switching. A high diversity of Klebsiella was found in silver gulls at all levels, which appears to be unique to this host species. Further, while there was some capacity for the coexistence of Klebsiella, it appears that this may also be primarily in the context of the wider microbial community. The phylogenetic diversity of lineages was unaffected by host range, collection date and differences in resistance cargo. However, it was significantly increased by differences in virulence cargo and decreased by differences in mobile genetic elements. Host range also did not significantly impact the persistence of lineages. These results imply that while there is evidence of host switching in Klebsiella, the factors studied here are quite complex and require an in-depth analysis of multiple hosts and bacterial genera to explain pathogen evolution in wildlife best.

FoR codes (2020)

310203 Computational ecology and phylogenetics, 310409 Microbial taxonomy, 310410 Phylogeny and comparative analysis

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.