The origin and evolution of appendages.

摘要: Current awareness of gene expression patterns and developmental mechanisms involved in the outgrowth patterning animal appendages contributes to our understanding origin evolution these body parts. Nevertheless, this vision needs be complemented by a new adequate comparative framework, context factorial notion homology. It may even profitable categorize as also gut diverticula, ingrowths 'virtual appendages' such eye spots on butterfly wings. Another unwarranted framework is Cartesian co-ordinate system onto which are currently described where it supposed that one exists for each separate axis. justified, instead, look correspondences between main axis same animal, latter might source growth gave rise former. This hypothesis paramorphisms contrasted with current co-option. Recapitulationism common fault Evo-Devo perspectives concerning appendages, evolutionary often expected key ontogenetic inception appendage formation. perspective evident debate nature default arthropod appendage. Most likely, never did exist, first probably developed along trunk an already patterned extensively antero-posterior