DIVERGENCE IN MORPHOLOGY AND MATING SIGNALS, AND ASSORTATIVE MATING AMONG POPULATIONS OF CHORTHIPPUS-PARALLELUS (ORTHOPTERA, ACRIDIDAE)

Three geographically widely separated populations of the grasshopper C horthippus parallelus (Orthoptera: Acrididae) have been examined for m orphological divergence, divergence in characteristics of the acoustic sexual signals of males, and assortative mating. Significant assortat ive mating existed between two of the three pairwise combinations of p opulations in multiple-choice tests. This may be caused by divergence in three of the four acoustic signal parameters measured. The populati ons also differed in morphology, including characters associated with signal production. The results are discussed in relation to theories f or the origin of premating isolation, and it is argued that the observ ed divergence has developed rapidly, possibly indicating the action of selection. However, this selection could not have been caused by inte ractions with closely related taxa.