MORPHOLOGY, HISTOLOGY, AND FINE STRUCTURE Patterns of Genitalic Morphology Around Suture Zones in North American Lycaeides (Lepidoptera: Lycaenidae): Implications for Taxonomy and Historical Biogeography

Within the North American Lycaeides (Hübner) fauna, there are at least three major lineages thatexhibit extensivemorphological andecological variation, especially at suturezoneswhere these lineages meet. We examined male genitalic morphology inLycaeidespopulations spanning much of North America to evaluate the current taxonomy and to address questions about the patterns of morphological variation at suture zones and potential evolutionary processes responsible for the patterns. Our genitalic measurements were based on those of V. Nabokov who revised North American Lycaeides taxonomy in the 1940s. Canonical discriminant analysis validated NabokovÕs original species designations, but it did not support many of his subspeciÞc designations. Populations at a suture zone in the Great Lakes region are similar to populations on the east side of this zone. Populations at a western suture zone in the Sierra Nevada and adjacent ranges exhibit intermediate morphology between lineages on either side of this suture zone. We tested the hypothesis that contemporary gene ßow contributes to the patterns of morphology in suture zones by testing for the increased variance in quantitative traits that is expected in a hybrid swarm. Based on a comparison of variances from populations within and outside of these suture zones, there is no evidence of current hybridization between lineages, with the sole exception of the population sample from the White Mountains of eastern California. The intermediate morphology and the general absence of increased variance within western suture zone populations imply that hybridization may have been important in the evolution of North American Lycaeides.