Does limb length predict the relative energetic cost of locomotion in mammals?

Abstract

Do relatively longer limbs result in a lower energetic cost of locomotion? To determine whether or not cost is correlated with limb length in some way other than that due to their respective relationships to body mass, we have removed the effects of size by calculating the residuals of the relationship between each character and body size. We then regressed the pairs of residuals on one another. Because biological variables do not occur in a series of units that have evolved independently, the degree of divergence of two species is likely to be influenced by the length of time since they last shared a common ancestor. We therefore corrected for the phylogenetic relatedness of species. Data on the energetic cost of locomotion of a wide variety of species were taken from published sources. Data on limb lengths were taken from specimens in various museum collections which were similar in body mass (± 12%) to the specimens on which the cost measurements were made. None of the correlations between the residuals of either fore‐ or hindlimb length and neither of two estimates of the cost of locomotion was significant at P = 0.05. It is concluded that limb length does not importantly influence an animal's locomotor efficiency. These results do not imply the lack of a close relationship between cost and stride length.