Variation in male wing song characters in Drosophila plantibia (Hawaiian picture-winged Drosophila group)

The males of most species of the Hawaiian Drosophila planitibia group produce songs when vibrating their wings during courtship. In four of the most recently evolved species, D. differens, D. planitibia, D. heteroneura, and D. silvestris, these songs are simple in structure and possess a higher and more variable carrier frequency than the songs of the more ancestral species of the group. In the present paper, we studied the variation in wing song production and song characters in a D. planitibia population. Some males vibrated their wings at a very low amplitude or slow speed, producing no detectable sound. Other males produced sound bursts varying in carrier frequency and burst length. The carrier frequency of the song depended mainly on the wing posture of the male during wing vibrations and was consistent for individual males. Variation between males of different isofemale progenies was not significant in any measured song trait. Songs of the males recorded in the present study differed, however, from songs of the males of a laboratory strain recorded earlier.