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Faculty-Student Research Featured in Journal of Insect Physiology

January 8, 2007

julian center snow.jpgJanuary 8, 2007, Greencastle, Ind. - Research conducted by faculty members and students in DePauw University's department of biology is published in the January 2007 edition of the Journal of Insect Physiology. The article is entitled, "The proximate control of pupal color in swallowtail butterflies: Implications for the evolution of environmentally cued pupal color in butterflies (Lepidoptera: Papilionidae)." It details the work of recent graduates Matt Jones, Lauren Rakes and Gabe Dunn; current student Marisa Yochum; and Wade N. Hazel, professor of biology, and Kevin S. Kinney associate professor of biology.

Stacey Wurster, now a graduate of Earlham College, also participated in the project. The work was supported by a National Science Foundation grant to DePauw.

An abstract of the article states: "The environmentally cued production of cryptic green/yellow or brown/melanized pupae is widespread in butterflies, occurring in the Nymphalidae, Pieridae, and the Papilionidae subfamily Papilioninae. The dimorphism is controlled by the hormone pupal melanization reducing factor (PMRF). In the nymphalid Inachis io dibutryl cAMP mimics PMRF, and inhibits pupal melanization. However, in the papilionid Papilio polyxenes PMRF stimulates browning, suggesting that the control of pupal color by PMRF has evolved independently in the swallowtail and nymphalid–pierid lineages. We examined this hypothesis by using ligatures to prevent hormone release in five species representing three Papilioninae tribes. One species, Papilio glaucus, produces only brown pupae. Ligatures resulted in green cuticle posterior to the ligature in all five swallowtail species, including P. glaucus, suggesting that the mode of action of PMRF is the same in the three tribes. We also found that in P. polyxenes Insect Physiology Jan 2007.gifinjections of dibutryl cAMP into prepupal larvae mimic the effect of PMRF, by causing dose-dependent pupal browning. Our results support the hypothesis that the control of pupal color by PMRF has evolved independently in the two lineages. The observation that green pupal color can be induced in P. glaucus by ligature indicates that environmentally cued pupal color could evolve by facultative inhibition of PMRF release."

The journal's reviewers call the work "an important and very interesting comparative study" and state the "manuscript is well written, presents a detailed and logical interpretation of the results and focuses in a phylogenetic view."

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