'University of Zagreb, Faculty of Science, Department of Mathematics'
Abstract
Wildlife harbors a substantial and largely undocumented diversity of RNA viruses and microbial life forms. RNA viruses and microbes are also arguably the most diverse and dynamic entities on Earth. Despite their evident importance, there are major limitations in our knowledge of the diversity, ecology, and evolution of RNA viruses and microbial communities. These gaps stem from a variety of factors, including biased sampling and the difficulty in accurately identifying highly divergent sequences through sequence similarity-based analyses alone. The implementation of meta-transcriptomic sequencing has greatly contributed to narrowing this gap. In particular, the rapid increase in the number of newly described RNA viruses over the last decade provides a glimpse of the remarkable diversity within the RNA virosphere. The central goal in this thesis was to determine the diversity of RNA viruses associated with wildlife, particularly in an Australian context. To this end I exploited cutting-edge meta-transcriptomic and bioinformatic approaches to reveal the RNA virus diversity within diverse animal taxa, tissues, and environments, with a special focus on the highly divergent "dark matter" of the virome that has largely been refractory to sequence analysis. Similarly, I used these approaches to detect targeted common microbes circulating in vertebrate and invertebrate fauna. Another important goal was to assess the diversity of RNA viruses and microbes as a cornerstone within a new eco-evolutionary framework. By doing so, this thesis encompasses multiple disciplines including virus discovery, viral host-range distributions, microbial-virus and host–parasite interactions, phylogenetic analysis, and pathogen surveillance. In sum, the research presented in this thesis expands the known RNA virosphere as well as the detection and surveillance of targeted microbes in wildlife, providing new insights into the diversity, evolution, and ecology of these agents in nature
