Evolutionary trade-offs in locomotor capacities in lacertid lizards: are splendid sprinters clumsy climbers?


BiekeVanhooydonck, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium. Tel.: +32 3820 22 81; fax: +32 3820 22 71; e-mail: vhooyd@uia.ac.be


We tested the hypothesis that an evolutionary trade-off exists between the capacity to run on level terrain and the ability to climb inclined structures in lacertid lizards. Biomechanical and physiological models of lizard locomotor performance suggest that the morphological design requirements of a ground-dwelling vs. scansorial life style are difficult to reconcile. This conflict is thought to preclude simultaneous evolution of maximal locomotor performance on level and inclined terrain. This notion has been corroborated by comparative studies on lizard species from other groups (Anolis, Chamaeleo, Sceloporus), but is not supported by our data on 13 species from the family Lacertidae. We found no indication of a negative association between maximal sprint speed of lizards over a level racetrack (indicative of ground-dwelling locomotor performance), on an inclined stony surface (indicative of climbing performance over rock faces) and inclined mesh surface (indicative of clambering performance among vegetation). Moreover, morphological characteristics associated with fast sprinting capacities (e.g. long hind limbs) apparently enhance, rather than hinder climbing and clambering performance. We conclude that in our sample of lacertid lizards, the evolution of fast sprinting capacity on level terrain has not inflicted major restrictions on climbing and clambering performance.