CAREER: The coevolution of an eavesdropper sensory system in response to an ever evolving communication system

Saint Olaf College, Northfield MN

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Signals in animal communication can evolve in response to actions from intended and unintended receivers. When signals change, it is unclear how sensory systems adapt, and respond to modification in signal features. The parasitoid fly Ormia ochracea eavesdrops on cricket calling songs to locate suitable host crickets to lay eggs on or near and parasitism results in cricket death. This pressure has driven the rapid development of novel calling songs among several populations of the Pacific field cricket in Hawaii, but not among other host cricket species in the continental United States. This creates a unique opportunity to track changes in the auditory system of an eavesdropper that may be attributed to differences in acoustic experience, behavioral plasticity, and the propensity to learn novel signals in response to signal evolution. The researcher will elucidate song features that O. ochracea evaluate to recognize cricket calling songs, track changes in the auditory system in response to signal change, and determine the role of auditory experience and learning in exploiting novel songs across populations over time. This research will be used to develop course-based undergraduate research experiences (CUREs) that will broaden access to genuine research in the classroom. Research findings will also be applied to develop a portable pop-up museum exhibit on animal communication through a collaborative multidisciplinary effort between students in biology and art. Both educational aims seek to increase interest in STEM fields. Since the conceptualization of the ‘receiver psychology’ framework, it has been recognized that the ‘psychology of receivers’ plays a significant role in shaping the evolution of communication signals. As signals evolve between senders and intended receivers, eavesdroppers must also adapt to changing signals. How this occurs in eavesdroppers, and its impacts on shaping the sensory systems underlying behavioral decisions is poorly known. Addressing these unresolved questions requires a better understanding of the eavesdropper’s receiver psychology, which includes the detectability, discriminability, and memorability of ancestral and novel signals. The researcher will determine signal detection and recognition thresholds from Ormia ochracea while performing walking phonotaxis on a high-speed treadmill system. To quantify the sensory basis of signal detection at the biomechanical level of analysis, laser Doppler vibrometry will be applied to characterize the frequency response of the tympanum and to determine its ability to detect ancestral and novel songs. At the neural level of analysis, neural signal detection thresholds will be quantified using extracellular recordings of auditory evoked potentials from the ascending auditory pathway. Across its geographic range in North America, Ormia ochracea are known to parasitize different host cricket species that produce different species-specific calling songs. Behavioral, biomechanical, and neural levels of analyses will be applied to characterize population level differences in the detection and recognition of ancestral cricket songs, and the role of auditory experience in learning to exploit novel song types. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.