Locomotion, Energetics, Performance, and Behavior: A Mammalian Perspective on Lizards, and Vice Versa.

摘要: SYNOPSIS Animals are constrained by their abilities and interactions with environmental factors, such as low ambient temperatures. These constraints range from physical impossibilities to energetic inefficiencies, may entail trade-offs. Some of the related locomotion activity metabolism can be illustrated through allometric comparisons mammals lizards, representative terrestrial vertebrate endotherms ectotherms, respectively, because these lineages differ greatly in aerobic metabolic capacities, resting costs, thermoregulatory patterns. Allometric both useful unavoidable, but "outlier" species (unusual for clade) also inform evolutionary scenarios, they help indicate extremes possible adaptation within mammalian saurian levels organization. We compared lizards standard rate (SMR), maximal oxygen consumption during forced exercise (VO2max), net (incremental) cost transport (NCT), speed (MAS), daily movement distance (DMD), energy expenditure (DEE) active season, ecological (ECT = percentage DEE attributable locomotion). (Snakes were excluded limbless has no counterpart mammals.) only considered lizard SMR, VO2max, NCT, MAS, sprint data if measured at 35-40 °C. On average, MAS is ∼7.4-fold higher mammals, whereas SMR VO2max ∼6-fold greater, values all three traits overlap (or almost overlap) between a fact that not previously been appreciated. Previous studies show speeds similar smaller larger sizes fast some mammals. Mammals move further each day than DMD far most variable trait here, NCT similar. exceed ∼11.4-fold DEE. average lineages, ECT surprisingly low, somewhat positively allometric. If mammal 100 g body mass entire could do so ∼21 17 min, thus de-emphasizing importance time constraints. conclude ecological-energetic relatively more likely occur large, carnivorous lizards. Overall, our support idea (gradual) evolution endothermy did necessarily require major changes locomotor energetics, performance, or associated behaviors. Instead, we speculate responses temperatures (e.g., shivering) have key "difficult" step this transition.