Song characteristics and morphological traits in four populations of the grasshopper Chorthippus biguttulus L.
We investigated four populations of the grasshopper Chorthippus biguttulus with respect to differences in morphological traits and characteristics of their communication signals. A special focus was laid on possible correlations between morphological and song traits of males that could be used by females to infer quality cues of potential mates. We also tested whether females exhibit preferences for males of their own population. Specific song features (onset accentuation, offset, syllable period) of males—but not of females—differed between populations. We observed size differences both in males and females from different populations, but the size ranks of the two sexes were not always correlated. Environmental factors appear to have a strong influence on different size traits, compared to genetic origin. In all populations a specific song feature, the accentuation of syllable onsets, showed a similar correlation with a morphological trait, hind leg size, but its correlation with other size indicators sometimes differed in sign. Females did not prefer songs of males from their own population. The best predictor for song attractiveness was—unexpectedly—not the onset accentuation but the offset depth.