Sprint performance of a generalist lizard running on different substrates: grip matters

Abstract

The relationships between locomotor performance and major features of environmental structure, such as incline and diameter, have been consistently identified in several vertebrate groups. The effects of variation in characteristics such as texture and structural complexity, in contrast, remain neglected, and associations between sprint speeds achieved during steady-level locomotion and the way an animal grips the surface are particularly obscure. In the present study, we have used the habitat generalist lizard Tropidurus torquatus to test the hypothesis that animals run faster on the substrates where gripping performance is higher. We ran 18 individuals on seven different substrates (wood, thin and coarse sand, coarse gravel, rock, leaf litter and grass) and recorded their maximum speeds using high-speed cameras. Surfaces were characterized for height variation and grip, the last given by average grip performance achieved by lizards of different sizes. Maximum sprint speeds were highest on rock and grass and lowest on thin and coarse sand, and variation in performance among substrates was explained by grip: substrates in which lizards gripped stronger are those that enhanced average maximum sprint speed. This study is the first report providing evidence for variation in maximum sprint speeds achieved by a generalist lizard running on different substrates, and demonstrates how friction resulting from the interaction of the lizard with the substrate may be critically important for sprint speed.

When a general morphology allows many habitat uses

“…It should be noted that this generalized morphology seems absent in Tropidurus lizards, which have demonstrated to be more versatile (Grizante et al 201.0). The lineage, however, also includes generalist species such as the lizard Tropidurus torquatus and Tropidurus etheridgei, which use a broad variety of environments and exhibit suitable performance in physically contrasting surfaces (Vitt 1991;Cruz et al 1998;Brandt et al 2015). A next step, therefore, may consist of incorporating locomotor performance of tropidurids and liolaemids running along a wide range of surface types in order to directly access the functional implications of generalized morphologies in different ecological settings…”

City slickers: poor performance does not deter Anolis lizards from using artificial substrates in human‐modified habitats

“…Previous studies of the effects of substrate on locomotor performance in lizards have focused primarily on variation in substrate inclination and diameter (Huey & Hertz ; Losos & Sinervo ; Spezzano & Jayne ), but fewer studies have assessed the effects of substrate texture or roughness (but see Tulli, Abdala & Cruz ; Brandt, Galvani & Kohlsdorf ; Vanhooydonck et al . ).…”

“…). Using a lizard habitat generalist, Tropidurus torquatus , Brandt, Galvani & Kohlsdorf () found a positive relationship between grip strength and maximum sprint speed across seven different types of substrate on a level track. They argue that friction coefficients resulting from the interaction between a lizard's foot and substrates of varying roughness are an important determinant of sprint speed (Alexander ), not to mention critical for maintaining a secure grip on vertical surfaces to prevent slipping and falling.…”

“…Previous studies of the effects of substrate on locomotor performance in lizards have focused primarily on variation in substrate inclination and diameter (Huey & Hertz 1982;Losos & Sinervo 1989;Spezzano & Jayne 2004), but fewer studies have assessed the effects of substrate texture or roughness (but see Tulli, Abdala & Cruz 2012;Brandt, Galvani & Kohlsdorf 2015;Vanhooydonck et al 2015). Using a lizard habitat generalist, Tropidurus torquatus, Brandt, Galvani & Kohlsdorf (2015) found a positive relationship between grip strength and maximum sprint speed across seven different types of substrate on a level track. They argue that friction coefficients resulting from the interaction between a lizard's foot and substrates of varying roughness are an important determinant of sprint speed (Alexander 2003), not to mention critical for maintaining a secure grip on vertical surfaces to prevent slipping and falling.…”

Tree selection is linked to locomotor performance and associated noise production in a lizard

“…Invertebrate prey can also use auditory cues to detect advancing predators (Hoy, 1992;Miller & Surlykke, 2001;Fournier et al, 2013). Additionally, lizard sprint speed, a factor likely to be important in escape from predators (Foster et al, 2015) and the efficacy of prey capture (Vanhooydonck, Herrel & Van Damme, 2007), differs according to substrate characteristics (Tulli, Abdala & Cruz, 2012;Brandt, Galvani & Kohlsdorf, 2015). However, potential links between substrate use and substrate effects on noise and locomotor ability have, to our knowledge, not been tested.…”