Lauder George V, Shaffer H Bradley
School of Biological Sciences, University of California, Irvine, California 92717.
J Morphol. 1988 Sep;197(3):249-268. doi: 10.1002/jmor.1051970302.
The process of metamorphosis in tiger salamanders, Ambystoma tigrinum, is used to investigate motor pattern conservatism in vertebrates. Specifically, we examined cranial muscle activity to determine if changes in the motor pattern are correlated with the morphological or environmental changes that occur at metamorphosis. Twenty-three variables were measured from electromyographic recordings from six cranial muscles in 13 tiger salamanders. These variables described the configuration of the motor pattern: the peak amplitude of activity, duration, relative onset, and time to peak amplitude were measured for each of the six muscles. Univariate and multivariate statistical analyses showed that there was no change in the mean motor pattern associated with the morphological transformation at metamorphosis: larval and metamorphosed individuals feeding in the water have very similar motor patterns. This was true despite significant morphological changes in the design of the feeding mechanism at metamorphosis and despite a significant decrease in aquatic feeding performance following metamorphosis. There was a change in the mean motor pattern to jaw muscles when metamorphosed individuals fed in water and on land: metamorphosed terrestrial feedings tend to have longer bursts of muscle activity then do aquatic feedings. The environmental changes in the motor pattern cannot be attributed to effects of differing fluid density or viscosity between water and air and are instead related to the shift to feeding by tongue projection on land. The decrease in aquatic feeding performance that occurs after metamorphosis is not correlated with changes in the motor pattern. Instead, the results suggest that changes in behavioral performance during ontogeny are associated with the transformation of hydrodynamic design of the feeding mechanism from uni- to bidirectional, and that motor patterns driving complex rapid behaviors may be conserved when behavior is altered by changes in peripheral morphology.
虎螈（Ambystoma tigrinum）的变态过程被用于研究脊椎动物运动模式的保守性。具体而言，我们检查了头部肌肉活动，以确定运动模式的变化是否与变态时发生的形态或环境变化相关。从13只虎螈的6块头部肌肉的肌电图记录中测量了23个变量。这些变量描述了运动模式的配置：测量了6块肌肉中每块肌肉的活动峰值幅度、持续时间、相对起始时间和达到峰值幅度的时间。单变量和多变量统计分析表明，与变态时的形态转变相关的平均运动模式没有变化：在水中进食的幼体和成体具有非常相似的运动模式。尽管变态时进食机制的设计发生了显著的形态变化，并且变态后水生进食性能显著下降，但情况依然如此。当变态后的个体在水中和陆地上进食时，颌部肌肉的平均运动模式发生了变化：变态后的陆地进食往往比水生进食具有更长的肌肉活动爆发时间。运动模式的环境变化不能归因于水和空气之间不同的流体密度或粘度的影响，而是与在陆地上通过舌投射进食的转变有关。变态后发生的水生进食性能下降与运动模式的变化无关。相反，结果表明个体发育过程中行为表现的变化与进食机制的流体动力学设计从单向到双向的转变有关，并且当行为因外周形态的变化而改变时，驱动复杂快速行为的运动模式可能是保守的。
