Rising above the noise: The influence of population dynamics on the evolution of acoustic signaling

Abstract

Acoustic signaling is employed by many sexually reproducing species to select for mates and enhance fitness. However, signaling in dense populations can create an auditory background, or chorus, which can interfere with a signal receiver’s phonotactic selectivity, or the ability to distinguish signals. Feedback between the strength of an individual’s signal, phonotactic selectivity, and population size, may interactin complex ways to impact the evolution of the signaling trait within a population, potentially leading to the emergence of silence. Here we formulate a general model that captures the dynamic feedback between individual acoustic signalers, phonotactic selectivity, and the populationlevel chorus to explore the eco-evolutionary dynamics of an acoustic trait. We find that population dynamics has a significant influence on the evolutionary dynamics of the signaling trait, and that very sharp transitions separate conspicuous from silent populations. Our framework also reveals that increased phonotactic selectivity promotes the stability of signaling populations. We suggest that understanding the relationship between factors influencing population size such as environmental productivity, as well as factors influencing phonotactic selectivity such as anthropogenic noise, are central to understanding the complex mosaic of acoustically signaling and silent populations.