Dissecting the repeatability of female choice in the grasshopper Chorthippus biguttulus

Repeatable differences in preference between females are a prerequisite for the evolution of female choice. Existing studies have concentrated on the repeatability of female preference for the male trait eliciting the highest female response but have rarely dealt with female choosiness and response rate, which are also important traits for the evolution of female choice and can mimic repeatable variation in preference. We used a method devised to disentangle the effects of preference, choosiness and response rate to examine the repeatability of female choice for acoustic signals in the grasshopperChorthippus biguttulus . We stimulated females with artificial courtship signals that varied in one signal trait and recorded the number of acoustic responses of the females in two sessions separated by several days. Using a normal distribution function within a nonlinear regression between signalling trait and female response rate, we independently calculated values for female preference, choosiness and maximum response rate for the two sessions. All three aspects of female choice showed significant repeatability indicating large differences between females. This method will also be suitable for measuring the heritability of female preference, a crucial question regarding the evolution of female choice. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.