Genomics of Tasmanian devils and their transmissible cancer
The Tasmanian devil is the world’s largest extant marsupial carnivore and plays a vital ecological role on the island of Tasmania, Australia. Tasmanian devil populations are critically threatened by a highly virulent pathogen known as devil facial tumour disease (DFTD). DFTD is particularly remarkable because it is a transmissible cancer, with transmission between devils occurring via biting behaviours that result in tumor cells from one individual entering the wounds of another and growing uncontrollably from there. Individuals infected with DFTD typically die within one year of infection. DFTD has had a devastating impact on devil populations since its emergence in 1996, spreading across its entire geographic range and resulting in population declines exceeding 90%. However, devil populations are persisting at low densities despite early predictions of extinction. In my postdoctoral research, I am addressing several questions exploring associations between devil dispersal and DFTD spread, understanding spatiotemporal variation in DFTD transmission, and examining transcriptomic responses of devils to DFTD (and vice versa). My work forms part of a larger collaborative effort aimed at understanding the ecology and evolution of DFTD, led by Andrew Storfer, Menna Jones, Hamish McCallum, Rodrigo Hamede, and Paul Hohenlohe and funded by the NSF and NIH.
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Landscape factors shaping host connectivity and pathogen dynamics in urban bobcats
Urbanisation is a leading cause of habitat fragmentation and loss globally. Urban habitat fragmentation is a major factor affecting wildlife connectivity and can therefore have substantial impacts on wildlife disease transmission. However, few studies examine disease transmission and spread in urban environments. My PhD research at the University of Tasmania focused on implementing genetic approaches to understand relationships between host connectivity, pathogen transmission, and landscape heterogeneity in urban populations of bobcat in southern California. Using landscape genetic approaches, I found that urbanisation has a pervasive impact on bobcat connectivity, acting at both regional and local spatial scales to reduce bobcat gene flow. From these same bobcats, I also sequenced DNA from feline immunodeficiency virus (FIV), an apathogenic retrovirus that is endemic to many wild felid populations. By reconstructing phylogenetic relationships between FIV isolates, I was able to identify co-structuring of FIV with host populations and identify major road barriers to disease transmission. Further, I used phylogenetic relationships between FIV isolates across space and back through time to identify historical processes of urbanization that led to the reduced wildlife connectivity we see today. The rate at which FIV phylogenetic lineages spread across the landscape also appeared to be influenced by vegetation, with the denser vegetation found in natural areas associated with increased FIV spread. By integrating genetic data from both host and pathogen with landscape features within a single framework. These insights provide valuable information for managing an urban wildlife host-pathogen system, while showcasing the utility of landscape genetics and emerging ecological phylogenetic tools for studying connectivity in heterogeneous landscapes. My research formed part of a large collaboration funded by the NSF, led by Sue VandeWoude, Chris Funk, Kevin Crooks, Scott Carver, and Meggan Craft.
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Landscape genetics of Tasmanian wedge-tailed eagles
For my Honours research at the University of Tasmania, I used DNA from museum specimens to understand genetic variation of the Tasmanian wedge-tailed eagle, a large, endangered raptor that is endemic to the island of Tasmania. I found, contrary to expectations, genetic structure in this highly mobile species across a relatively small geographic area, which may reflect intrinsic dispersal behaviours such as philopatry. Although I am no longer actively involved in eagle research, there is a LOT of fascinating work being done to better understand this system. For instance, check out the brilliant James Pay, who is now using GPS telemetry to gain a detailed understanding of wedge-tailed eagle flight behaviour, tracking individuals in virtually real-time as they travel thousands of kilometres around Tasmania.
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