Abstract
Viruses that infect fish are understudied, yet they provide important evolutionary context to the viruses that infect terrestrial vertebrates. We surveyed gill tissue meta-transcriptomes collected from two species of native freshwater fish from Aotearoa New Zealand—Retropinna retropinna and Gobiomorphus cotidianus. A total of 64 fish were used for gill tissue meta-transcriptomic sequencing, from populations with contrasting life histories—landlocked (i.e., lacustrine) and diadromous—on the South Island and Chatham Islands. We observed that both viral richness and taxonomic diversity were significantly associated with life history and host species, with lacustrine R. retropinna characterised by higher viral alpha diversity than diadromous R. retropinna. Additionally, we observed transcripts of fish viruses from 12 vertebrate host-associated virus families, and phylogenetically placed eight novel RNA viruses and three novel DNA viruses in the Astroviridae, Paramyxoviridae, Orthomyxoviridae, Rhabdoviridae, Totiviridae, Poxviridae, Alloherpesviridae, and Adintoviridae in their evolutionary contexts. These results represent an important survey of the viruses that infect two widespread native fish species in New Zealand, and provide insight useful for future fish virus surveys.
Highlights
Fish represent basal evolutionary lineages to all extant terrestrial vertebrate species [1].Like all organisms, fish are susceptible to viral infection and have likely co-diverged with many viral groups over long evolutionary timescales
Revealing the viruses that infect fish species is useful for understanding the timescale of virus evolution and the relative frequency of virus–host co-divergence versus cross-species virus transmission [2], and provides useful evolutionary context to the viruses that infect higher vertebrates [3]
Aotearoa New Zealand separated from the Gondwanan supercontinent ca. 85–82 million years ago as part of the subcontinent Zealandia—known as Te Riu-a-Māui in Te Reo
Summary
Fish represent basal evolutionary lineages to all extant terrestrial vertebrate species [1].Like all organisms, fish are susceptible to viral infection and have likely co-diverged with many viral groups over long evolutionary timescales. Revealing the viruses that infect fish species is useful for understanding the timescale of virus evolution and the relative frequency of virus–host co-divergence versus cross-species virus transmission [2], and provides useful evolutionary context to the viruses that infect higher vertebrates [3]. The Zealandia continental waka carried unique Gondwanan species into ecological isolation, and during this process, early mammalian lineages became extinct [6]. This unique ecological isolation resulted in many endemic and native species of insects, birds, reptiles, and fish [7,8,9,10]. Analysis of the viruses that infect these endemic species provides an opportunity to identify whether this vicariance event has left an impression on virus ecology and evolution
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