Local population density and group composition influence signal-preference relationships in Enchenopa treehoppers (Hemiptera: Membracidae)

Many animals exhibit social plasticity—changes in phenotype or behavior in response to experience with conspecifics—that change how evolutionary processes like sexual selection play out. Here, we asked whether social plasticity arising from variation in local population density in male advertisement signals and female mate preferences influences the form of sexual selection. We manipulated local density and determined whether this changed how the distribution of male signals overlapped with female preferences—i.e., the signal-mate preference relationship. We specifically look at the shape of female mate preference functions, which, when compared to signal distributions, provide hypotheses about the form of sexual selection. We used Enchenopa binotata treehoppers, a group of plant feeding insects that exhibit natural variation in local densities across individual host plants, populations, species, and years. We measured male signal frequency and female preference functions across the den...