McElroy Eric J, Hickey Kristin L, Reilly Stephen M
Ohio Center for Ecology and Evolutionary Studies and Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
J Exp Biol. 2008 Apr;211(Pt 7):1029-40. doi: 10.1242/jeb.015503.
Foraging mode has molded the evolution of many aspects of lizard biology. From a basic sit-and-wait sprinting feeding strategy, several lizard groups have evolved a wide foraging strategy, slowly moving through the environment using their highly developed chemosensory systems to locate prey. We studied locomotor performance, whole-body mechanics and gaits in a phylogenetic array of lizards that use sit-and-wait and wide-foraging strategies to contrast the functional differences associated with the need for speed vs slow continuous movement during foraging. Using multivariate and phylogenetic comparative analyses we tested for patterns of covariation in gaits and locomotor mechanics in relation to foraging mode. Sit-and-wait species used only fast speeds and trotting gaits coupled with running (bouncing) mechanics. Different wide-foraging species independently evolved slower locomotion with walking (vaulting) mechanics coupled with several different walking gaits, some of which have evolved several times. Most wide foragers retain the running mechanics with trotting gaits observed in sit-and-wait lizards, but some wide foragers have evolved very slow (high duty factor) running mechanics. In addition, three evolutionary reversals back to sit-and-wait foraging are coupled with the loss of walking mechanics. These findings provide strong evidence that foraging mode drives the evolution of biomechanics and gaits in lizards and that there are several ways to evolve slower locomotion. In addition, the different gaits used to walk slowly appear to match the ecological and behavioral challenges of the species that use them. Trotting appears to be a functionally stable strategy in lizards not necessarily related to whole-body mechanics or speed.
觅食模式塑造了蜥蜴生物学许多方面的进化。从基本的坐等式短跑觅食策略出发，一些蜥蜴群体进化出了广泛的觅食策略，利用其高度发达的化学感应系统在环境中缓慢移动以定位猎物。我们研究了一系列蜥蜴的运动表现、全身力学和步态，这些蜥蜴采用坐等式和广泛觅食策略，以对比觅食过程中速度需求与缓慢持续移动需求相关的功能差异。通过多变量和系统发育比较分析，我们测试了步态和运动力学与觅食模式相关的协变模式。坐等式物种仅使用快速速度和小跑步态，并伴有奔跑（弹跳）力学。不同的广泛觅食物种独立进化出较慢的运动，采用行走（跳跃）力学并伴有几种不同的行走步态，其中一些步态已经进化了多次。大多数广泛觅食者保留了坐等式蜥蜴中观察到的小跑步态的奔跑力学，但一些广泛觅食者进化出了非常缓慢（高负荷因子）的奔跑力学。此外，三次向坐等式觅食的进化逆转与行走力学的丧失相关。这些发现提供了有力证据，表明觅食模式驱动了蜥蜴生物力学和步态的进化，并且有几种方式可以进化出较慢的运动。此外，用于缓慢行走的不同步态似乎与使用它们的物种的生态和行为挑战相匹配。小跑似乎是蜥蜴中一种功能稳定的策略，不一定与全身力学或速度相关。
