Demography and adaptation of a species specific pollinator associated with an invasive fig tree

Some fig species introduced outside of their native range have become invasive when colonized by their obligate pollinating wasps, but how these pollinators migrated and adapted to novel environments are less studied. Here, we focus on Eupristina verticillata, the obligate pollinating wasp of an invasive fig tree species (Ficus microcarpa), to uncover its demography and the molecular basis for adaptations to novel environments. We find that only one of the three cryptic species colonized in the sampling locations outside of its native range. This dominant cryptic species migrated simultaneously from the native range to the Americas and to the Mediterranean c. 130 years ago. Moreover, selective sweep analyses reveal several positively selected genes associated with adaptations to the nonnative range. Genome-wide association detect a nonsynonymous substitution in a dopamine N-acetyltransferase gene significantly linked with brood size. Our study outlines the route to colonization and genetic adaptations of an invasive mutualism.