Ipi

100 ms figure 11.1 (a) A train of a pulse song of D. birchii with polycyclic sound pulses (CN 4 to 5 cycles/pulse, PL around 12 msec, IPI around 30 msec and frequency around 400 Hz). Number of pulses in the pulse train (PN) is nine and the length of the pulse train (PTL) 250 msec. (b) A sine song of D. serrata with a carrier frequency of about 140 Hz and a burst length (BL) of 230 msec. (c) A pulse train of D. montana consisting of eight sound pulses (PN) with PTL of 380 msec. Among the pulse characters CN is around 5 cycles/pulse, PL around 20 msec and IPI around 35 msec. The carrier frequency of the song is about 300 Hz. (d) The first two pulses of a pulse train of D. littoralis consisting of long sound pulses (PL around 40 msec, CN around 12 cycles/pulse, IPI around 300 msec and frequency around 320 Hz).

temperature, which has to be taken in account when recording the songs (Hoikkala, 1985; Noor and Aquadro, 1998).

In addition to males, females also may produce acoustic cues during courtship. Ewing and Bennet-Clark (1968) reported that the "buzz" is essentially the same in all species of the melanogaster and obscura groups. Closer inspection of female songs has revealed species differences, e.g. in the virilis group (Satokangas et al., 1994) and in the bipectinata complex of the melanogaster subgroup (Crossley, 1986). Female songs are generally more irregular than the male songs.

In D. melanogaster, antennal hearing organs mediate the detection of conspecific songs in females and the arista tips of male and female antennae are moderately tuned to frequencies around 425 Hz (Gopfert and Robert, 2002). Sensory feed-back seems to play an important role also in shaping the courtship song in Drosophila, as males with auditory mutations are not able to produce normal song (Tauber and Eberl, 2001). Tauber and Eberl (2003) have reviewed acoustic communication in Drosophila focusing on the proximate, neural aspects of sound production and hearing.

In the present review I shall first give an overview on song variation between and within various Drosophila species and then go through the studies on the inheritance of male song characters using classical crossing experiments, quantitative genetic methods and gene transfer techniques. Finally there will be a short discussion on major questions concerning the evolution of species-specific courtship songs in Drosophila species.

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