EVOLUTIONARY CONSERVATISM OF OVIPOSITION PREFERENCE IN A WIDESPREAD POLYPHAGOUS INSECT HERBIVORE, PAPILIO ZELICAON

We analyzed geographic differentiation in oviposition preference in th e anise swallowtail butterfly, Papilio zelicaon Lucas, which is one of the most widely distributed and polyphagous butterflies in western No rth America. Among 13 populations that span 1200 km of the range of P. zelicaon in the Pacific Northwest of North America, the overall ovipo sition preference hierarchy has not diverged significantly, even thoug h these populations differ in the plant species they use in the field. The results indicate that differences in host availability and use ha ve not favored major reorganizations in the preference hierarchy of ov ipositing females. In stead, this butterfly has a conserved preference hierarchy that varies within a narrow range among populations. All po pulations ranked the four test plant species in the same overall relat ive order, even though these populations differ in the plant species t hey use in the field.