What’s the point? The functional role of claws in pad-bearing taxa (Gekkota: Diplodactylidae)
Data files
Jul 24, 2025 version files 322.20 MB
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alldata.RData
322.14 MB
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alldata.summ.RData
19.29 KB
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attachment.csv
851 B
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covariates.csv
1.43 KB
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emmeans.csv
1.74 KB
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Pillai_et_al._2025_Attachment_analysis.Rmd
6.21 KB
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Pillai_et_al._2025_Figures.R
9.54 KB
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Pillai_et_al._2025_Shear_force_analysis.Rmd
4.87 KB
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ptvh.csv
16.09 KB
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README.md
4.46 KB
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relative.probs.csv
214 B
Abstract
Morphological adaptations enable effective movement within habitats. Claws are among the most common adaptations that allow organisms to use inclined and vertical surfaces. However, some taxa have evolved adhesive pads in addition to claws, with claws suggested to be more effective at gripping coarse surfaces, while pads attach better to fine surfaces. Using test surfaces that represented the range of surface roughness used by six species of diplodactylid geckos in nature, we quantified the role of claws and pads acting together, and of pads alone. We examined two functional traits, attachment (on inclines, 45°, and vertical surfaces, 90°) and clinging ability (on inclines only). Claws were critical to attachment on vertical surfaces, and attachment declined linearly with decreasing surface roughness. Although attachment was lowest on fine-grained surfaces, this was where claws had the greatest functional contribution. Clinging ability also declined linearly with decreasing surface roughness, where claws played an additive role. Our study highlights novel results describing the function of gecko adhesive systems on different surfaces and suggests a clade-specific interaction of claws and pads. Specifically, we highlight that pads alone can be capable of attachment on rough surfaces, with claws contributing more on fine-grained surfaces.
https://doi.org/10.5061/dryad.9w0vt4brd
Pillai et al., 2025
Scripts for analysis
- Pillai_et_al._2025_Attachment_analysis.Rmd
- Pillai_et_al._2025_Figures.R
- Pillai_et_al._2025_Shear_force_analysis.Rmd
Data
Pillai et al. 2025 Attachment analysis
alldata.RData -
This file contains 3 measures of shear force per individual gecko on 3 orientations and 3 substrates (P40, Coarse sandpaper; P60, Intermediate sandpaper, and P80, Fine sandpaper). Explanations of columns below -
Force.X..N. = Force in the X direction (Newton)
Forxe Y..N. = Force in the Y direction (Newton)
Force Z..N. = Force in the Z direction (Newton)
Torque.X..N.mm. = Force in the X direction (Newton)
Torque.Y..N.mm. = Force in the Y direction (Newton)
Force Z..N.mm. = Force in the Z direction (Newton)
species = Species
location = TSV, Townsville; LNG, Longreach; HV, Hidden Valley; WND, Windorah, and WIN, Winton in Queensland, Australia.
id = Individual gecko id
replicate = replicate number
substrate = P40, Coarse sandpaper; P60, Intermediate sandpaper and P80, Fine sandpaper
orientation = 0, horizontal; 45, incline, and 90, vertical (degrees)
axis = direction of force
claw = C, claw intact and NC, claw clipped
alldata.summ.RData -
This file contains the summarised version of alldata.Rdata, i.e., maximum value of 3 measures of shear force per individual gecko on 3 orientations and 3 substrates (P40, Coarse sandpaper; P60, Intermediate sandpaper, and P80, Fine sandpaper)
Explanations of columns below -
species.x = Species
id = Individual gecko id
substrate = P40, Coarse sandpaper; P60, Intermediate sandpaper and P80, Fine sandpaper
orientation = horizontal, incline, and vertical
axis = direction of force applied
claw = C, claw intact and NC, claw clipped
attach = H, horizontal surface so attachment did not fail, A, successful attachment, and N = Failed attachment
Force.X..N. = Force in the X direction (Newton)
Force.Z..N. = Force in the Z direction (Newton)
genus = Genus
habitat = arboreal, rock-dwelling, generalist, or shrub-dwelling
covariates.csv -
This file contains the covariates, namely mass, toepad area (tpa), and snout-vent length (svl), used in both analyses
genus = Genus
species = Species
id = Individual gecko id
mass = mass (gram)
tpa = toepad area (mm)
svl = snout-vent-length (mm)
ptvh.csv -
This file contains measures of peak-to-valley heights (surface roughness) from test substrates and microhabitats in nature
species = Species of diplodactylid gecko for associated surface measures
id = Individual gecko id
Microhabitat = Tree, Rock, Shrub, or Test sandpaper
type = Species name of trees/shrubs; dead trees/shrubs; rock type; Coarse (P40 sandpaper), Intermediate (P60 sandpaper); Fine (P80 sandpaper)
ptvh = Peak-to-valley height (µm)
habitat = arboreal, rock-dwelling, generalist, or shrub-dwelling
category = Nature of the substrate (natural or test surface)
attachment.csv -
This file contains the outputs of the glmmTMB model used to analyse the probability of attachment (Figure 2). Explanations of columns below -
Orientation = Incline (45 degrees); Vertical (90 degrees)
Treatment = 'Claws intact' or 'Claws clipped'
prob = Probability of falling off
SE = Standard error
attach_prob = Probability of attachment
Substrate = Coarse (P40 sandpaper), Intermediate (P60 sandpaper); Fine (P80 sandpaper)
emmeans.csv -
This file contains the outputs of the model used to analyse clinging ability (shear force generation) with or without claws. Explanations of columns below -
Treatment = 'Claws intact' or 'Claws clipped'
Substrate = Coarse (P40 sandpaper), Intermediate (P60 sandpaper); Fine (P80 sandpaper)
Habitat = arboreal, rock-dwelling, generalist, or shrub-dwelling
response = Estimated marginal least square means of the shear force with and without claws
SE = Standard error
df = Degrees of freedom
relative.probs.csv -
This contains the contribution of claws, which is 1 - the contribution of pads only from the output of the glmmTMB model used to analyse the probability of attachment. Explanations of columns below -
Orientation = Incline (45 degrees); Vertical (90 degrees)
Substrate = Coarse (P40 sandpaper), Intermediate (P60 sandpaper); Fine (P80 sandpaper)
relative.prob = contribution of claws to attachment
