PHENOTYPIC VARIATION IN THE MATING PREFERENCES OF FEMALE FIELD CRICKETS, GRYLLUS INTEGER

Phenotypic variation in the mating preferences of female field cricket s was examined. Males of this species produce a trilled calling song w hich varies in the number of pulses per trill, the inter-trill interva l and the proportion of missing pulses within a trill. As a population , females preferred male calling songs with more pulses per trill and shorter inter-trill intervals in two-speaker choice tests, but did not discriminate between male song that varied in the proportion of missi ng pulses. Female preference functions were examined by sequentially p resenting females with a series of songs that varied in only one param eter. As a population, the strength of the female preference for male calling song appeared to increase with the number of pulses per trill in the song. However, there was no significant variation in the streng th of the preference for male calling song with either the inter-trill interval or proportion of missing pulses in the song. There was signi ficant variation between individual females in their preference functi ons based on the number of pulses per trill and the inter-trill interv al in male song, but not based on the proportion of missing pulses in male song. Females appeared to differ in how strongly they preferred m ore pulses per trill. In contrast, females appeared to differ not only in the strength of their preference based on inter-trill interval, bu t also in whether they preferred longer or shorter inter-trill interva ls. The repeatability of preference functions within females was relat ively high for number of pulses per trill (0.50) and inter-trill inter val (0.59), but low for proportion of missing pulses (-0.02). Correlat ions between female preference functions were also examined. Females t hat strongly preferred more pulses per trill tended to strongly prefer shorter inter-trill intervals. In addition, females that strongly pre ferred shorter inter-trill intervals tended to prefer a higher proport ion of missing pulses. These results suggest that selection can act on female preference functions in field crickets, and that direct select ion on one preference function can result in indirect selection on oth er preference functions.