Genotypic variation in calling song and female preferences of the field cricket Teleogryllus oceanicus

Abstract

Geographically isolated populations often show phenotypic divergence in traits important in reproduction. A large proportion of the phenotypic variation in temporal parameters of the calling song of the field cricket Teleogryllus oceanicus is related to geographical location. Similarity between the songs recorded in different populations reflects geographical proximity. I used a common-garden breeding experiment to determine whether differences between the songs of two populations from the extremes of the geographical and phenotypic distribution (Oahu, Hawaii and Cairns, Australia) have a genetic basis. Differences in the total song duration and the proportion of the long-chirp element in the song remained after five generations of common-garden breeding, indicating that the populations had diverged genetically for these traits. Differences in a third song trait, the intervals between sound pulses and chirps, disappeared after common-garden breeding, suggesting that either the difference between populations in these traits represents phenotypic plasticity or the populations converged as a result of adaptation to the laboratory environment. A prospective analysis of the patterns of genetic variation within populations is presented. Full-sib analyses suggested high levels of genetic variability in song traits. Family mean covariance matrices suggested that populations differ in the genetic architecture of their songs. Females from both populations preferred songs with a high proportion of the long-chirp element, and preferences appeared to have high genetic and residual variability, although the sampling variances on these parameters were high. There was little evidence of a correlation between female preference for the long-chirp element and the amount of the long-chirp element produced by their brothers.