In order to understand the role of AMP deaminase and the mechanism of its genetic evolution, several animal models were investigated for their use as accurate experimental models. Experimental evidence is given that, within elasmobranch fish, the ancestral AMP deaminase gene has evolved to the muscle-type enzyme. Therefore, using these models, the mechanisms of the genetic amplification and duplication of the AMP deaminase gene can be investigated as well as the problem of the role of the enzyme in muscular function.