Complex movement patterns: Modifiability and constraints

Most behaviours involve complex morphological systems and vice versa morpho logical systems are used by the organism in many different ways. During evo lution and ontogeny changes in kinematics and function of skeletal and musc ular systems must be coordinated with changes in their neural control. Neur omotor patterns are sometimes believed to be conserved in evolution, leadin g to diversification at the level of musculoskeletal design. Vertebrate mot or patterns used in feeding are reviewed to examine this hypothesis. Stereo typed behaviour is not necessarily the result of phylogenetic constraints b ut may also result from the functional demands imposed by the mechanics of the jaw apparatus and the nature of the task performed. Sensory feedback an d descending control not only contribute to 'online' control of movement bu t also shape the development of motor patterns and learning behaviour and i ndicate a potentially large flexibility. The neural and sensory apparatus t hat produces this flexibility will be subject to evolutionary modification. In the absence of a demand for flexibility motor patterns may become stere otyped in some species, while they are very flexible in others. To the exte nt that morphological systems perform independent movements during differen t behaviours, separate basic motor patterns may be required, which may be c oordinated in different ways.