The evolution and frequency of female color morphs in Holarctic Odonata: why are male-like females typically the minority?

Abstract

Abstract We compiled data on the occurrence and frequency of distinct female variants among Holarctic Odonata and interpreted the data in light of harassment-based hypotheses. The major source of male confusion for male mimicry hypotheses is predicted to be signal similarity between andromorphs and male distractors; for the learned mate recognition hypothesis (LMR), it is predicted to be variation in female signals. Mapping morphism state onto molecular phylogenies of Ischnura and Enallagma failed to resolve the general ancestral female condition. However, it appeared that the andromorphic state may be ancestral in one case, and that blue structural colors were ancestral to orange and green pigmentations. Of the polymorphic species surveyed, 13% had more than two morphs, 4% had multiple heteromorphs but no andromorph, and 7% of ‘monomorphic’ congeners were functionally polymorphic because developmental variants mate. Such female signal variation lies beyond the scope of simple male mimicry, but neverthele...