Overlooking the smallest matter: viruses impact biological invasions.

Parasites and pathogens have recently received considerable attention for their ability to affect biological invasions, however, researchers have largely overlooked the distinct role of viruses afforded by their unique ability to rapidly mutate and adapt to new hosts. With high mutation and genomic substitution rates, RNA and single-stranded DNA (ssDNA) viruses may be important constituents of invaded ecosystems, and could potentially behave quite differently from other pathogens. We review evidence suggesting that rapidly evolving viruses impact invasion dynamics in three key ways: (1) Rapidly evolving viruses may prevent exotic species from establishing self-sustaining populations. (2) Viruses can cause population collapses of exotic species in the introduced range. (3) Viruses can alter the consequences of biological invasions by causing population collapses and extinctions of native species. The ubiquity and frequent host shifting of viruses make their ability to influence invasion events likely. Eludicating the viral ecology of biological invasions will lead to an improved understanding of the causes and consequences of invasions, particularly as regards establishment success and changes to community structure that cannot be explained by direct interspecific interactions among native and exotic species.