DOI: 10.5061/dryad.9w0vt4brd
title: What’s the point? The functional role of claws in pad-bearing taxa (Gekkota: Diplodactylidae)

description: 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.
description: # What's the point? The functional role of claws in pad-bearing taxa
 (Gekkota: Diplodactylidae) 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