Author ORCID Identifier
Date of Award
Department or Program
Ecology, Evolution, Environment and Society
Hannah ter Hofstede
The challenge of attracting and locating potential mates has driven the evolution of diverse mate-finding signaling systems. These systems can be complex, with multiple signals or signal components spread across different sensory modalities. When multiple modalities are combined in one communication system, features of each can be important to individual fitness; over evolutionary time, these can shape investment in different parts of a signal repertoire. One group of animals that commonly uses multiple signal modalities is Orthoptera. Cricket and katydid species within this order often produce airborne sound calls to advertise to potential mates. Many also produce substrate-borne vibrational signals. I describe three investigations into the patterns of sound and vibration use by orthopteran insects with a combination of long focal recordings of individual callers and playback experiments to receivers. In the first chapter, I quantify the total diel sound and vibrational calling activity of ten species of katydid (Tettigoniidae: Pseudophyllinae) to investigate whether these signal types trade off with each other. I find that species that use more vibration tend to use less sound, and that other traits like sound call bandwidth may mediate this relationship. In the second chapter, I investigate intraspecific variation in one of these species (Docidocercus gigliotosi), recording the calling activity of recently mated vs. unmated males over several weeks. I find evidence for positive within-individual, but not among-individual, correlations between sound and vibrational signaling, with mating having large initial effects and more subtle, lingering ones on signal production. In the third chapter, I assess how duetting female crickets (Lebinthus bitaeniatus, Gryllidae: Eneopterinae) respond to different components of male calls, finding that callers strike a balance between calling signal attractiveness and efficacy in duet timing. Increasing the length of a typically stereotyped sound call component results in vibrational replies that are higher amplitude and likely more perceptible—yet incorrectly timed. Together, these projects reveal patterns of differential investment in multiple signal modalities in orthopteran insects. Quantifying these differences is key to understanding how complex signaling systems function and how they might affect responses to environmental change.
Kernan, Ciara E., "Airborne Sound and Substrate-borne Vibration in Orthopteran Communication" (2023). Dartmouth College Ph.D Dissertations. 162.