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Do arms races punctuate evolutionary stasis? Unified insights from phylogeny, phylogeography and microevolutionary processes


  • Hirokazu Toju is studying co-evolutionary interactions from the aspects of population genetics, phylogenetics and microevolutionary selection, focusing mainly on the arms race involving long-mouthed insects and their plant partners. Teiji Sota is interested in adaptive divergence, speciation, species-assemblage process and phylogeogprahy and studies several arthropod groups.

Hirokazu Toju, Fax: +81-29-861-6080;


One of the major controversies in evolutionary biology concerns the processes underlying macroevolutionary patterns in which prolonged stasis is disrupted by rapid, short-term evolution that leads species to new adaptive zones. Recent advances in the understanding of contemporary evolution have suggested that such rapid evolution can occur in the wild as a result of environmental changes. Here, we examined a novel hypothesis that evolutionary stasis is punctuated by co-evolutionary arms races, which continuously alter adaptive peaks and landscapes. Based on the phylogeny of long-mouthed weevils in the genus Curculio, likelihood ratio tests showed that the macroevolutionary pattern of the weevils coincides with the punctuational evolution model. A coalescent analysis of a species, Curculio camelliae, the mouthpart of which has diverged considerably among populations because of an arms race with its host plant, further suggested that major evolutionary shifts had occurred within 7000 generations. Through a microevolutionary analysis of the species, we also found that natural selection acting through co-evolutionary interactions is potentially strong enough to drive rapid evolutionary shifts between adaptive zones. Overall, we posit that co-evolution is an important factor driving the history of organismal evolution.