Nonlinear variation in clinging performance with surface roughness in geckos

Pillai, Rishab, Nordberg, Eric, Riedel, Jendrian, and Schwarzkopf, Lin (2020) Nonlinear variation in clinging performance with surface roughness in geckos. Ecology and Evolution, 10 (5). pp. 2597-2607.

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Understanding the challenges faced by organisms moving within their environment is essential to comprehending the evolution of locomotor morphology and habitat use. Geckos have developed adhesive toe pads that enable exploitation of a wide range of microhabitats. These toe pads, and their adhesive mechanisms, have typically been studied using a range of artificial substrates, usually significantly smoother than those available in nature. Although these studies have been fundamental in understanding the mechanisms of attachment in geckos, it is unclear whether gecko attachment simply gradually declines with increased roughness as some researchers have suggested, or whether the interaction between the gekkotan adhesive system and surface roughness produces nonlinear relationships. To understand ecological challenges faced in their natural habitats, it is essential to use test surfaces that are more like surfaces used by geckos in nature. We tested gecko shear force (i.e., frictional force) generation as a measure of clinging performance on three artificial substrates. We selected substrates that exhibit microtopographies with peak-to-valley heights similar to those of substrates used in nature, to investigate performance on a range of smooth surfaces (glass), and fine-grained (fine sandpaper) to rough (coarse sandpaper). We found that shear force did not decline monotonically with roughness, but varied nonlinearly among substrates. Clinging performance was greater on glass and coarse sandpaper than on fine sandpaper, and clinging performance was not significantly different between glass and coarse sandpaper. Our results demonstrate that performance on different substrates varies, probably depending on the underlying mechanisms of the adhesive apparatus in geckos.

Item ID: 62502
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: adaptation, adhesion biomechanics, ecomechanics, gekkota, physiology, zoology
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Copyright Information: © 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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A version of this publication was included as Appendix II of the following PhD thesis: Riedel, Nils Jendrian (2020) Evolution and ecological adaptations of microornamentation in Australian geckos (Gekkota, Squamata). PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Skyrail Rainforest Foundation
Date Deposited: 11 Mar 2020 07:45
FoR Codes: 31 BIOLOGICAL SCIENCES > 3109 Zoology > 310908 Animal physiology - biophysics @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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