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Density-dependent predation influences the evolution and behavior of masquerading prey

Lookup NU author(s): Dr John Skelhorn

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Abstract

Predation is a fundamental process in the interaction between species, and exerts strong selection pressure. Hence, anti-predatory traits have been intensively studied. Although it has long been speculated that individuals of some species gain protection from predators by sometimes almost-uncanny resemblances to uninteresting objects in the local environment (such as twigs or stones), demonstration of antipredatory benefits to such "masquerade" have only very recently been demonstrated, and the fundamental workings of this defensive strategy remain unclear. Here we use laboratory experiments with avian predators and twig-mimicking caterpillars as masqueraders to investigate (i) the evolutionary dynamics of masquerade; and (ii) the behavioral adaptations associated with masquerade. We show that the benefit of masquerade declines as the local density of masqueraders relative to their models (twigs, in our system) increases. This occurs through two separate mechanisms: increasing model density both decreased predators' motivation to search for masqueraders, and made masqueraders more difficult to detect. We further demonstrated that masquerading organisms have evolved complex microhabitat selection strategies that allow them to best exploit the density-dependent properties of masquerade. Our results strongly suggest the existence of opportunity costs associated with masquerade. Careful evaluation of such costs will be vital to the development of a fuller understanding of both the distribution of masquerade across taxa and ecosystems, and the evolution of the life history strategies of masquerading prey.

Publication metadata

Author(s): Skelhorn J, Rowland HM, Delf J, Speed MP, Ruxton GD

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences

Year: 2011

Volume: 108

Issue: 16

Pages: 6532-6536

Print publication date: 19/04/2011

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences

URL: http://dx.doi.org/10.1073/pnas.1014629108

DOI: 10.1073/pnas.1014629108

PubMed id: 21464318

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