Segregation of F-2 interspecific hybrid growth performance and wing color patterns relative to parental species in the Papilio machaon species group (Lepidoptera: Papilionidae)

A strange Papilio female specimen with a prominent yellow wing band type very much like P. brevicauda (and also seen in P. machaon, and P. zelicaon) was captured in the forested mountains of southwest Vermont, USA. Despite its brevicauda- like appearance, it had mt-DNA of P. polyxenes. In eastern North America the P. brevicauda (Maritime Provinces of Canada) is currently believed to reflect previous (ancient) hybridization between ancestral P. machaon and P. polyxenes. It is uncertain whether the brevicauda-like wing trait features in the odd Vermont female may be a result of some introgression of P. machaon or P. brevicauda with P. polyxenes in eastern North America as seen also in the Ozark Mountains with P. joanae. Nonetheless, the significance of wing trait analyses in relation to hybrid zones with P. polyxenes remains relevant. The segregation of wing color patterns and hostplant use abilities (efficiencies and growth rates) were examined for laboratory hand-paired F-2 hybrids of P. zelicaon x Papilio polyxenes relative to the parental species and primary hybrids. The black adult color pattern characterizing P. polyxenes is presumed to be inherited as a simple autosomal dominant. These hybrids were examined to determine: (i) how F-1 primary hybrid offspring perform relative to the parental types in survival, growth rates, and growth efficiencies; and (ii) whether these larval traits and the adult color patterns might be linked with wing morphology in the F-2 hybrids. While the F-1 hybrids grew as well as the P. polyxenes parent (P. zelicaon was significantly less efficient and slower in growth than either of these), we could not convincingly determine whether the growth performances of the F-2 segregants were linked with the parental wing patterns.