Benefits of female mate choice in the grasshopper Chorthippus biguttulus: an overview of the experimental evidence
In the grasshopper Chorthippus biguttulus, males produce acoustic courtship signals by rubbing stridulatory pegs on their hind legs against a protruding wing vein. A female listening to an attractive male song may respond with acoustic signaling. The male then approaches the responding female phonotactically and mating usually occurs.
This communication system provides a rare opportunity to study female mating preferences in detail as female response to playbacks of natural or artificial signals can be measured and quantified. Exploiting this behavior we could show that males differ in attractiveness and we detected several song traits influencing male attractiveness. Varying one of these signal traits, syllable pause duration, we were able to show that individual females differ in response rate, choosiness and preference. Females mating with attractive males did not produce offspring with higher fitness nor is local adaptation revealed in the males’ signals.
The only evidence we could find is that females prefer male songs that are easier to differentiate from hetero-specific signals. Recently, however, we discovered another possible benefit of mate choice: song traits preferred by females are produced by males with smaller genomes. We interpret these data as adaptive female mate choice selecting against deleterious selfish genetic elements.