Doctoral Thesis
Ornate Kangaroo Tick (Amblyomma triguttatum) in Western Australia: Environmental Drivers of Population Structure and Exploration of Microbial Communities
Murdoch University
Doctor of Philosophy (PhD), Murdoch University
2025
DOI:
https://doi.org/10.60867/00000080
Abstract
Ticks are ectoparasites of major medical and veterinary importance, transmitting a wide range of pathogens to humans, companion animals, and livestock. As extreme weather events, wildfires, habitat destruction, and biodiversity loss increasingly reshape ecosystems, these changes affect tick ecology and consequently pathogen transmission dynamics. Effective disease control policies depend on identifying source populations, predicting range expansions, and understanding how landscape features influence tick movement, critical information that population genetic tools provide by quantifying gene flow and revealing dispersal corridors across heterogeneous environments.
This research applied population genetic tools to Amblyomma triguttatum (ornate kangaroo tick), a poorly studied but widely distributed species well known for its contact with humans, companion animals, livestock and wildlife. The project aimed to: i) identify optimal molecular tools for tick population genetic analysis through a comprehensive 50-year chronological literature review evaluating cost, reproducibility, resolution, and throughput, complemented by laboratorybased empirical work; ii) characterise population genetic structure using double digest Restriction-Site Associated DNA Sequencing (ddRADseq) on 379 specimens collected from the Swan Coastal Plain, Western Australia; iii) determine environmental drivers of genetic di"erentiation by examining climate, soil, and land cover data; and iv) examine associations between population structure and microbial community composition through bacterial profiling to identify microbiome patterns and taxa of interest.
ddRADseq was identified as the optimal tool, balancing cost-effectiveness with information yield. Population analysis revealed subtle isolation-by-distance patterns across the ~500 x ~30 km study area, with increasing vegetation positively correlated with genetic connectivity whilst urban areas and water bodies reduced it. No associations were found between population structure and microbiome composition. These findings indicate gradual host-mediated dispersal through the landscape, with vegetation corridors and host-impermeable barriers influencing distribution patterns. The lack of population-microbiome correlation suggests individual tick biology or host blood meal drive microbial community composition rather than geographic factors. As Australian ecosystems undergo rapid transformation, these findings provide foundational information critically needed to predict and manage emerging tick-borne disease risks.
Details
- Title
- Ornate Kangaroo Tick (Amblyomma triguttatum) in Western Australia: Environmental Drivers of Population Structure and Exploration of Microbial Communities
- Authors/Creators
- Xavier W Barton
- Contributors
- Charlotte Oskam (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthShane Tobe (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthJoe Fontaine (Supervisor) - Murdoch University, School of Environmental and Conservation Sciences
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Publisher
- Murdoch University
- Identifiers
- 991005869307607891
- Murdoch Affiliation
- School of Medical, Molecular and Forensic Sciences
- Resource Type
- Doctoral Thesis
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