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.

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Forests worldwide are essential goods for humanity as they provide support, provision, regulation, and cultural ecosystem services. In Brazil, the Atlantic Forest has lost much of its original cover, is currently represented by relatively small fragments in an anthropized matrix. Therefore, it is very relevant to analyze if forest fragments change in related the fragmentation of the original native vegetation and how they maintain their quality. This study aimed to analyze whether patch-level metrics are related to forest quality (biotic integrity) and whether relief features such as headboards are related to forest fragmentation patterns to provide subsidies for public planning and environmental conservation policies. The methodology involved mapping forest fragments (F) and drainage headboards (DH), calculating patch-level metrics (AREA, SHAPE, PROX), and the biotic integrity (BII) of the forest. Spearman's Correlation Coefficient was used to test the relationship between variables. The results showed a significative robust relationship between AREA and BII and significative medium relationship between SHAPE and DH, confirming partially the initial assumptions of the research. We concluded that the integrity of the forest fragment and the presence of drainage headboards must be considered in public planning and environmental conservation policies.