Calling songs of sympatric and allopatric populations of Cicada barbara and C. orni (Hemiptera: Cicadidae) on the Iberian Peninsula

Calling songs of the sibling species Cicada barbara and C. orni were studied in sympatric and allopatric populations on the Iberian Peninsula, where the distribution ranges of both species overlap. No difference was found in any acoustic property for the sympatric and allopatric populations of C. barbara studied and only one variable (minimum frequency) was significantly different between sympatric and allopatric populations of C. orni. No hybrids with intermediate songs were found and no character displacement in the calling song was detected. It is very likely that these species were already considerably differentiated when they met on the Iberian Peninsula. Particularly, premating (or even postmating) isolating mechanisms (according to Mayr's Biological Species Concept) or different specific-mate recognition systems (in the view of the Paterson's Recognition Concept of Species) were most likely already present, which prevented hybridization between this pair of species. It is assumed that the calling songs are the most important premating isolating mechanism corresponding to the specific-mate recognition systems of these species of cicadas.