Patterns of host–parasite coinvasion promote enemy release and specialist parasite spillover

Abstract

Species invasion and redistribution, driven by climate change and other anthropogenic influences, alter global biodiversity patterns and disrupt ecosystems. As host species move, they can bring their associated parasites with them, potentially infecting resident species, or leave their parasites behind, enhancing their competitive ability in their new ranges. General rules to predict why invading hosts will retain some parasites but not others are relatively unexplored, and the potential predictors are numerous, ranging from parasite life history to host community composition. In this study, we focus on the parasite retention process during host invasion. We used the Global Mammal Parasite Database to identify terrestrial mammal hosts sampled for parasites in both native and non‐native ranges. We then selected predictors likely to play a role in parasite retention, such as parasite type, parasite specialism, species composition of the invaded community, and the invading host's phylogenetic or trait‐based similarity to the new community. We modelled parasite retention using boosted regression trees, with a suite of 25 predictors describing parasite and host community traits. We further tested the generality of our predictions by cross‐validating models on data for other hosts and invasion locations. Our results show that parasite retention is nonrandom and predictable across hosts and invasions. It is broadly shaped by parasite type and parasite specialism, with more specialist parasites that infect many closely related hosts more likely to be retained. This trend is pronounced across parasite types; helminths, however, show a more uniform likelihood of retention regardless of specificity. Overall, we see that most parasites are not retained (11% retained), meaning many invasive species may benefit from enemy release. However, species redistribution does have the potential to spread parasites, and this also has great relevance to understanding conservation implications of species invasions. We see that specialist parasites are most likely to coinvade with their hosts, which suggests that species closely related to the invasive hosts are most likely to be affected by parasite spillover.

Human-aided dispersal and population bottlenecks facilitate parasitism escape in the most invasive mosquito species

“…Indeed, metabarcoding and qPCR analysis suggest that those two OTUs dominate the microbiota of intermediate and native populations but not that of recently introduced ones. A recent study on parasite infection in invasive species has shown that parasite characteristics are reliable to predict parasite retention ( 76 ). The authors even demonstrated that specialist parasites (like A. taiwanensis ) are usually more persistent to coinvade with their native host.…”

Human-aided dispersal and population bottlenecks facilitate parasitism escape in the most invasive mosquito species

“…Indeed, metabarcoding and qPCR analysis suggest that those two OTUs dominate the microbiota of intermediate and native populations but not that of recently introduced ones. A recent study on parasite infection in invasive species has shown that parasite characteristics is reliable to predict parasite retention (76). The authors even demonstrated that specialist parasites (like As.…”