Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals

Abstract Specular reflection appears as a bright spot or highlight on any smooth glossy convex surface and is caused by a near mirror-like reflectance off the surface. Convex shapes always provide the ideal geometry for highlights, areas of very strong reflectance, regardless of the orientation of t...

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Autores principales:	Samuel J. Waldron, John A. Endler, Janne K. Valkonen, Atsushi Honma, Susanne Dobler, Johanna Mappes
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/4b928926a7c94c1db8a96141f05e65d3
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spelling	oai:doaj.org-article:4b928926a7c94c1db8a96141f05e65d32021-12-02T12:30:10ZExperimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals10.1038/s41598-017-00217-52045-2322https://doaj.org/article/4b928926a7c94c1db8a96141f05e65d32017-03-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-00217-5https://doaj.org/toc/2045-2322Abstract Specular reflection appears as a bright spot or highlight on any smooth glossy convex surface and is caused by a near mirror-like reflectance off the surface. Convex shapes always provide the ideal geometry for highlights, areas of very strong reflectance, regardless of the orientation of the surface or position of the receiver. Despite highlights and glossy appearance being common in chemically defended insects, their potential signalling function is unknown. We tested the role of highlights in warning colouration of a chemically defended, alpine leaf beetle, Oreina cacaliae. We reduced the beetles’ glossiness, hence their highlights, by applying a clear matt finish varnish on their elytra. We used blue tits as predators to examine whether the manipulation affected their initial latency to attack, avoidance learning and generalization of warning colouration. The birds learned to avoid both dull and glossy beetles but they initially avoided glossy prey more than dull prey. Interestingly, avoidance learning was generalized asymmetrically: birds that initially learned to avoid dull beetles avoided glossy beetles equally strongly, but not vice versa. We conclude that specular reflectance and glossiness can amplify the warning signal of O. cacaliae, augmenting avoidance learning, even if it is not critical for it.Samuel J. WaldronJohn A. EndlerJanne K. ValkonenAtsushi HonmaSusanne DoblerJohanna MappesNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-10 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Samuel J. Waldron John A. Endler Janne K. Valkonen Atsushi Honma Susanne Dobler Johanna Mappes Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
description	Abstract Specular reflection appears as a bright spot or highlight on any smooth glossy convex surface and is caused by a near mirror-like reflectance off the surface. Convex shapes always provide the ideal geometry for highlights, areas of very strong reflectance, regardless of the orientation of the surface or position of the receiver. Despite highlights and glossy appearance being common in chemically defended insects, their potential signalling function is unknown. We tested the role of highlights in warning colouration of a chemically defended, alpine leaf beetle, Oreina cacaliae. We reduced the beetles’ glossiness, hence their highlights, by applying a clear matt finish varnish on their elytra. We used blue tits as predators to examine whether the manipulation affected their initial latency to attack, avoidance learning and generalization of warning colouration. The birds learned to avoid both dull and glossy beetles but they initially avoided glossy prey more than dull prey. Interestingly, avoidance learning was generalized asymmetrically: birds that initially learned to avoid dull beetles avoided glossy beetles equally strongly, but not vice versa. We conclude that specular reflectance and glossiness can amplify the warning signal of O. cacaliae, augmenting avoidance learning, even if it is not critical for it.
format	article
author	Samuel J. Waldron John A. Endler Janne K. Valkonen Atsushi Honma Susanne Dobler Johanna Mappes
author_facet	Samuel J. Waldron John A. Endler Janne K. Valkonen Atsushi Honma Susanne Dobler Johanna Mappes
author_sort	Samuel J. Waldron
title	Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
title_short	Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
title_full	Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
title_fullStr	Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
title_full_unstemmed	Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
title_sort	experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/4b928926a7c94c1db8a96141f05e65d3
work_keys_str_mv	AT samueljwaldron experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals AT johnaendler experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals AT jannekvalkonen experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals AT atsushihonma experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals AT susannedobler experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals AT johannamappes experimentalevidencesuggeststhatspecularreflectanceandglossyappearancehelpamplifywarningsignals
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Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals

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