Metapopulation structure of a seed-predator weevil and its host plants in arms race coevolution

Although the importance of gene flow in the geographic structuring of host–parasite interactions has been well discussed, little is known about how dispersal drives the spatial dynamics of other types of coevolutionary interactions in nature. We evaluated the roles of gene flow in the geographically structured processes of a predator–prey arms race involving a seed-predatory weevil with a long mouthpart and its host camellia plant with a thick fruit coat. Molecular genetic analyses showed that both weevil and camellia populations were structured at a spatial scale of several kilometers. Importantly, the spatial pattern of the migration of weevils, but not that of camellias, imposed significant effects on the geographic configuration of the levels of coevolutionary escalation. This result suggests that even if migration is limited in one species (camellia), local coevolution with the other species that migrates between neighboring localities (weevil) can reduce the inter-population diffe...