Tempo and Modes of Cultural Evolution in the Complex Display of the Superb Lyrebird

Cornell University, Ithaca NY

Investigators

Abstract

Australian lyrebirds are the most accomplished mimics of all animals. Wild lyrebirds learn to sing near-perfect renditions of the calls of other birds and many other natural sounds, while lyrebirds that live near people are exact mimics of car alarms, chainsaws, and even camera shutters. Yet lyrebirds do not learn only from their environment; they also learn sounds from other lyrebirds. This ability to first learn and then produce a great variety of sounds has many parallels to the ways that humans learn language and other components of our cultures, making lyrebirds an excellent species on which to conduct experiments about the basics of cultural learning and information exchange that would be impossible with human subjects. The Cornell University scientists leading this project will study lyrebirds across their range in Australia to document their learning ability and track the learned components of their songs. The scientists will conduct a series of experiments in which they 'seed' a new song into a group of lyrebirds and track how it is passed from one lyrebird to another, to better understand what kinds of factors are important in cultural learning. They will also take advantage of a historical experiment using a population of lyrebirds that was introduced into Tasmania in the 1930s, tracking how these lyrebirds retained their original songs while learning new ones. The team will generate a variety of public outreach materials using videos of lyrebird displays, and engage groups of US college students through a summer research program. Cultural evolution shapes the behavioral repertoires of many non-human animals, but the associated interactions among culture, genetics and ecological context remain poorly understood. Socially transmitted, multicomponent communication systems are of particular value for testing questions about the tempos and modes of cultural evolution. This project leverages the spectacular display behavior of a well-known vocal mimic, the superb lyrebird, to test a series of hypotheses about the tempos and modes of cultural evolution, using complementary comparative approaches and field-based experiments. Like humans, lyrebirds are excellent vocal mimics. In addition, they communicate using multi-component signals made up of both mimetic and non-mimetic song, and perform a complex dance display. Combined with limited dispersal and a large but patchy distribution, these attributes foster the development of diverse lyrebird 'cultures'. This project will first characterize geographic variation in audiovisual repertoires and compare this with genomic variation and divergence from local to metapopulation scales, accounting for ecological context. A temporal analysis of changes in acoustic displays, using archived recordings (1932-present), will complement the spatial analysis and strengthen conclusions regarding the tempo and mode of lyrebird cultural evolution. The project further capitalizes on a serendipitous experiment in which lyrebirds were introduced to an island (Tasmania) where they did not occur previously. Comparisons of lyrebird displays in translocated versus source population will be used to test the cultural lability of different display components. Finally, mechanisms of social transmission, and the cultural lability of lyrebird displays, will be tested directly using innovative field-based cultural transmission experiments. 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.