Randomly amplified polymorphic DNA evidence of introgression in two closely related sympatric species of coniferophagous Choristoneura (Lepidoptera: Tortricidae) in Atlantic Canada

Abstract

DNA was extracted from selected desiccated museum specimens of Choristoneura fumiferana (Clemens) and C pinus Freeman and analyzed by using the randomly amplified polymorphic DNA (RAPD) technique. Seventeen species-specific RAPD markers were used to differentiate between these 2 closely related and morphologically similar budworm species. Several morphologically atypical specimens of each budworm species were selected for analysis based on deviations from conventional descriptions of uncus shape and size, wing bands, maculation, and background coloration. Analysis of the distribution of species-specific markers in selected specimens from Atlantic Canada, where the 2 species are sympatric and their flight periods occasionally overlap, suggests that reproductive isolation of these 2 Choristoneura species is incomplete, thus providing the first evidence that hybridization of C. fumiferana and C. pinus has occurred in nature. The significance of these results to hybridization, introgression and retained ancestral polymorphism is discussed.