A rapidly evolving cricket produces percussive vibrations: how, who, when, and why

• Published in: Behavioral ecology Vol. 34; no. 4; pp. 631 - 641
• Main Authors: Wikle, Aaron W, Broder, E Dale, Gallagher, James H, Tinghitella, Robin M
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 10.07.2023
• Subjects: plasticity; courtship; purring cricket; drumming; rattling cricket
• ISSN: 1045-2249; 1465-7279
• DOI: 10.1093/beheco/arad031

Abstract Sexual signals are often transmitted through multiple modalities (e.g., visual and chemical) and under selection from both intended and unintended receivers. Each component of a multimodal signal may be more or less conspicuous to receivers, and signals may evolve to take advantage of available private channels. We recently documented percussive substrate-borne vibrations in the Pacific field cricket (Teleogryllus oceanicus), a species that uses airborne acoustic and chemical signals to attract and secure mates. The airborne signals of Hawaiian T. oceanicus are currently undergoing rapid evolution; at least five novel male morphs have arisen in the past 20 years. Nothing is yet known about the newly discovered percussive substrate-borne vibrations, so we ask “how” they are produced, “who” produces them (e.g., population, morph), “when” they produce them (e.g., whether they are plastic), and “why” (e.g., do they play a role in mating). We show that the vibrations are produced exclusively by males during courtship via foreleg drumming. One novel morph, purring, produces quieter airborne songs and is more likely to drum than the ancestral morph. However, drumming behavior is also contextually plastic for some males; when we removed the ability of males to produce airborne song, ancestral males became more likely to drum, whereas two novel morphs were equally likely to drum regardless of their ability to produce song. Opposite our prediction, females were less likely to mate with males who drummed. We discuss why that might be and describe what we can learn about complex signal evolution from this newly discovered behavior. Male Pacific field crickets recently evolved new songs to attract females while avoiding eavesdropping predators. We discovered that males also generate vibrations by drumming their legs during courtship singing. The males with new songs differ from ancestral males in how likely they are to drum both when they can and cannot sing (silenced). However, females do not appear to like drumming males. With this discovery we can learn about how different types of sexual communication coevolve.