Viruses may play diverse roles in biological invasions by either preventing or facilitating the establishment or spread of the invasive species. Introduced hosts commonly leave behind many viruses present in their native ranges, which may allow the host to achieve greater fitness in the new environment. They also introduce their viruses into the new environment, potentially resulting in viral transmission from invaders to native hosts, known as “spillover”. On the other hand, the invasive species may accumulate new viruses, acting as a reservoir and resulting in “spillback” into susceptible native populations.
As these processes are largely unexplored, we aim to study the impact of invasion on the virome of most successful invasive species of freshwater invertebrates in Europe, the signal crayfish Pacifastacus leniusculus. In our recent study, we have identified novel and divergent signal crayfish associated RNA viruses. We now aim to elucidate the potential differences in viral diversity and prevalence along signal crayfish invasion range in recently invaded Korana River, Croatia, where the signal crayfish is spreading successfully in both upstream and downstream directions. Recently established populations at invasion fronts co-occur with native congener (narrow-clawed crayfish, Pontastacus leptodactylus), which has been gradually displaced at invasion core sites. Therefore, we further aim to compare the viromes of co-occurring and phylogenetically related crayfish: the invasive signal crayfish and the native narrow-clawed crayfish Pontastacus leptodactylus. To address the dynamics of viromes` compositions and interconnectedness of native and invasive host viromes, an innovative and interdisciplinary approach is required. Therefore, we will combine the extensive sampling of mixed- and single-species population and control crayfish population, optimized sample preparation for non-targeted high-throughput sequencing followed by state-of-the-art bioinformatics analysis to explore the viral sequences detected in hepatopancreas tissue. Using statistical analysis, we will investigate the correlations and possible influence of measured intrinsic (condition index, histopathological scores, gene expression data) and extrinsic (mixed- and single-species population density) factors on the viral diversity and prevalence detected across the expanding invasion range. We will discover novel viruses, observe their morphology, analyze their phylogenetic relationships with known viruses and elucidate the within-host patterns of virus nucleotide diversity potentially revealing the adaptations that occur with inter-species transmission of viruses.
The proposed project will provide a breakthrough in understanding the influence of invasion processes on the virome of invasive and native species, which is relevant not only for the invasion of crayfish species and for our study system, but also in a wider context to understand the effects of biological invasions on the host-associated microbiomes. In addition, the valuable research tools developed for evaluation of crayfish associated viral diversity and crayfish condition will lay a foundation for understanding the largely overlooked causes and consequences of biological invasions for rapidly evolving viruses.
This is a postdoctoral project financed by Slovenian Research Agency (ARRS).
Project ID: Z1-50017
Duration: 1.11.2024 – 31.10.2026
