Begin by considering a relaxed muscle. in this state, the myosin molecules of the thick filaments are not in contact with the actin of the thin filaments, and adp and pi are bound to the myosin heads. an action potential on the muscle cell plasma membrane initiates contraction of the sarcomeres from this relaxed state.

Three different types of muscles are cardiac muscle, smooth muscle and skeletal muscle. The movement of muscle require the protein like actin, myosin and troponin.

The contraction and relaxation of muscle occurs in the sequential events.The cross bridge formation occurs by the myosin head with actin. The inorganic phosphate is released by myosin. The actin is pulled by myosin towards the sarcomere center. The binding of ATP with myosin occurs. The actin and myosin cross bridge breaks and the hydrolysis of ATP occurs by myosin. Finally, the extension of myosin heads.

Answer;
Genetic drift
The mechanism of evolution that would have caused this change is genetic drift.

Explanation;
Genetic drift refers to changes in allele frequencies due to random chance. Genetic drift will eventually lead to allele loss or fixation even in large populations, but will take many more generations to occur in large populations than small. It may rapidly alter allele frequencies when population size decreases; bottle neck effect and founder effect.