The significance of wing pattern diversity in the Lycaenidae: mate discrimination by two recently diverged species


James A. Fordyce, Section of Evolution and Ecology, OneShields Avenue, University of California, Davis, CA 95616, USA. Tel.: 530 7522225; fax: 530 7521449; e-mail:


Closely related species of lycaenid butterflies are determinable, in part, by subtle differences in wing pattern. We found that female wing patterns can act as an effective mate-recognition signal in some populations of two recently diverged species. In field experiments, we observed that males from a Lycaeides idas population and an alpine population of L. melissa preferentially initiate courtship with conspecific females. A morphometric study indicated that at least two wing pattern elements were important for distinguishing the two species: hindwing spots and orange crescent-shaped pattern elements called aurorae. We deceived male L. idas into initiating courtship with computer generated paper models of heterospecific females when these pattern elements were manipulated, indicating that the wing pattern elements that define the diversity of this group can be effective mate recognition signals.