Papilio glaucus and tulip trees

Although the adaptive value for maintenance of generalized feeding abilities are difficult to assess, it is possible to determine experimentally if post-ingestive suitability of a plant for growth of such herbivores improves with individual or population experience (i.e., local specialization). Studies are needed using plants or diets of known chemical quality under controlled environmental conditions. In addition, it is important to use individuals from different geographical locations, preferably those known to have different preferred natural hosts. 

The Eastern tiger swallowtail butterfly, Papilio glaucus, is the most poly-phagous of the 540 species of Papilionidae in the world (Munroe, 1960 Scriber, 1973). It occupies a geographical area which encompasses nearly 4 million square miles (including most of Canada and the Eastern half of the US). Two 

The Magnoliaceae is of tropical origin and is believed to be the ancestral host 

Total Northern group Middle group Southern group  

14 The numbers of different potential foodplants for Papilio glaucus (of the 20 favorites) which occur at different latitudes along the transect presented in Figs 7.12 and 7.13. The foodplant species are numbers from top to bottom (i.e.. Quaking aspen, Populus tremuloides, is 1, etc.). The plant transition zone is represented by shading. 

---