Abstract
The emergence of novel viruses is usually a result of viral host-jumping. Yet, the role ecological and host factors play in influencing viral host-jumping is poorly understood. While the advancement of metatranscriptomics and the ability to uncover entire viromes of hosts has revolutionised virus discovery, a historic sampling bias favouring medically or economically relevant host species has significantly limited our understanding of the diversity of the virosphere. It is crucial to continue to explore the virosphere to provide a more holistic understanding of the factors that impact viral diversity and emergence.
New Zealand’s native species are unique hosts in which to study viral evolution. Many of these hosts have been isolated for millions of years and, therefore, provide ideal models to study the evolution of their viruses. Nevertheless, almost nothing is known about the viruses harboured in New Zealand’s fauna. In this thesis, I aimed to reveal the viromes of some of New Zealand’s most iconic species: tuatara, bats, eels, skinks, and geckos. By doing so, this thesis will uncover new insights into viral diversity and the potential drivers of viral emergence.
In this body of work, I uncovered over 130 viruses, some of which were highly divergent, representing novel viral families. Factors including location, host specificity, host adaptive radiation, and the prolonged isolation of New Zealand following its split from the supercontinent Gondwana appeared to influence the virome composition of New Zealand’s vertebrate species sampled. Notably, none of the viruses uncovered in this thesis were associated with causing overt disease since all the sampled hosts were deemed healthy, highlighting the growing view that the vast majority of viruses are not pathogenic.
The viromes uncovered in this thesis can act as a baseline for future virological investigations, facilitating comparisons to monitor changes in virome composition over time and in response to external factors. This thesis has laid the groundwork for future virome studies to be conducted in New Zealand, demonstrating that by uncovering the viromes of New Zealand’s hosts we can enhance our understanding of the drivers of viral emergence and evolution more generally.