VANHOOYDONCK, B.*; VAN DAMME, R.; AERTS, P.: Trade-offs in the evolution of locomotor performance: are speed and stamina correlated in lacertid lizards?

Morphological and physiological considerations suggest that sprinting ability and endurance capacity put conflicting demands on the design of an animal’s locomotor apparatus, and therefore cannot be optimised simultaneously. To test this hypothesis, we correlated size-corrected maximal sprint speed and stamina of 12 species of lacertid lizards. Both raw species means and phylogenetically independent contrasts of sprint speed and stamina showed a significant negative relationship, giving support to the idea of an evolutionary trade-off between the two performance measures. To test the hypothesis that the trade-off is mediated by a conflict in morphological requirements, we correlated both performance traits with snout-vent length, size-corrected estimates of body mass and limb length, and relative hind limb length (the residuals of the relationship between hind and fore limb length). Fast running species had hind limbs that were long compared to their fore limbs. None of the other size and shape variables showed a significant relationship with speed or endurance. We conclude that the evolution of sprint capacity may be constrained by the need for endurance capacity and vice versa, but identification of the design conflict underlying this trade-off is needed to close the case.