Scriber, J. M. 1994. Climate legacies and sex chromosomes: latitudinal patterns of voltinism, diapause and host-plant selection in 2 species of swallowtail butterflies at their hybrid zone. Pages 133-171 in H. V. Danks, ed. Insect Life-Cycle Polymorphism: Theory, Evolution and Ecological Consequences for Seasonality and Diapause Control. Kluwer Academic, Dordrecht, Netherlands.
Seasonal thermal-unit accumulations drive plant growth and insect growth rates. This chapter describes the complex and interactive effects of latitudinal clines in seasonal degree-day accumulations and climate upon two swallowtail butterfly species, Papilio glaucus and P. canadensis (Lepidoptera). Specifically, their thermal environment is shown to have major effects on host-plant preferences of ovipositing females, diapause genetics, geographic limits to gene flow, voltinism differences, and body size. Latitudinal clines in insect adaptations (including co-adapted gene complexes on the sex chromosomes) are related to latitudinal clines in thermal-unit accumulation and climatic trends. Microgeographic variation in thermal-unit accumulations during the summer in northern Michigan and northern Wisconsin is correlated with certain life-history traits of P. canadensis, and may largely explain variation in adult body size and host selection that occurs within latitudes 45.0 °N to 46.5 °N.Sign in to download PDF back to index