Review of reproductive isolating barriers in Odonata

Premating reproductive isolating barriers in Odonata involve temporal, habitat, and ethological barriers to interspecific gene exchange. Differences in visual and tactile stimuli comprise the most important and effective barriers within the order. Mechanical isolation, in the classical sense of incompatible genitalia, has not been demonstrated. Separation of potential mates during tandem (nongenitalic union) has been interpreted in some groups as a type of mechanical isolation. Postmating barriers have not been researched, although several hybrid dragonflies have been reported. Speculation on isolating barriers far outweighs actual data. Studies are needed on the importance of tactile stimuli in Anisoptera and on the existence of mechanical isolation in both the genitalic and nongenitalic sense. Groups in which ethological isolation is expected but for which experimental studies do not exist are Gomphidae, Aeshnidae, Macromiidae, Corduliidae, Polythoridae, Megapodagrionidae, Pseudostigmatidae, Platystictidae, and Protoneuridae. The exact functions of the various structures used in mating still need to be clarified.