The main reason for the dramatic decline of the native american population of hispaniola from 1492 to 1542 was:

The main reason for the dramatic decline of the native American population of Hispaniola from 1492 to 1542 was the  introduction of diseases like smallpox, influenza and measles into the island. Since the people of Hispaniola lacked immunity to European pathogens, they fell prey to these terrible diseases.