Signal categorization by foraging animals depends on ecological diversity

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Abstract

Warning signals displayed by defended prey are mimicked by both mutualistic (Müllerian) and parasitic (Batesian) species. Yet mimicry is often imperfect: why does selection not improve mimicry? Predators create selection on warning signals, so predator psychology is crucial to understanding mimicry. We conducted experiments where humans acted as predators in a virtual ecosystem to ask how prey diversity affects the way that predators categorize prey phenotypes as profitable or unprofitable. The phenotypic diversity of prey communities strongly affected predator categorization. Higher diversity increased the likelihood that predators would use a 'key' trait to form broad categories, even if it meant committing errors. Broad categorization favors the evolution of mimicry. Both species richness and evenness contributed significantly to this effect. This lets us view the behavioral and evolutionary processes leading to mimicry in light of classical community ecology. Broad categorization by receivers is also likely to affect other forms of signaling.

Data availability

All data for this study are present in the supporting files, and source code to produce the figures from those files is included in the Supplementary RMarkdown file.

Article and author information

Author details

David William Kikuchi

Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, United States

For correspondence
dwkikuchi@gmail.com

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7379-2788
Anna Dornhaus

Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, United States

Competing interests
The authors declare that no competing interests exist.
Vandana Gopeechund

Department of Biology, Carleton University, Ottawa, Canada

Competing interests
The authors declare that no competing interests exist.
Thomas N Sherratt

Department of Biology, Carleton University, Ottawa, Canada

Competing interests
The authors declare that no competing interests exist.

Funding

National Institutes of Health (K12GM000708)

David William Kikuchi

Natural Sciences and Engineering Research Council of Canada

Thomas N Sherratt

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: Consent process is described in the Methods. Human subjects research was carried out with the permission of the Carleton University Research Ethics Board-B under permit number 13385 14-0276.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.