Figure 1.

The quantification and interpretation of the interaction coefficient Ψ in the present study. The y-axis indicates the focal female trait (choosiness, ) averaged among a sample of females. The x-axis indicates the average acoustic environment experienced by those females (). The prime () indicates that the male trait is expressed in an interacting partner or partners. The male genotypes that determine the interacting phenotype are indicated below the x-axis. The flatwing trait segregates as a sex-linked Mendelian trait, and T. oceanicus has an (X,X)/(X,O) sex determination system. Thus, the intensity of the acoustic environment scales with the proportion of flatwing alleles in a population. Hypothetical values of Ψ are indicated by the lines. A positive Ψ means that average female choosiness increases as the acoustic environment becomes noisier. In contrast, a negative Ψ describes a situation where females become less choosy with a noisier acoustic environment. When , the acoustic environment has no effect on female choosiness.