Mariposa is a planet settled by survivors of the SS Mariposa, whose people survived for centuries only by cloning themselves.
Mariposa is a planet named after the SS Mariposa, an Earth ship whose passengers founded colonies in the 22nd century. In Up the Long Ladder the Enterprise visited the second Mariposa colony, half a light year from Bringloid V, where only five survivors had lived through the ship's crash landing.
The colonists had kept their advanced technology and survived by cloning, but repeated copying was causing fatal errors in their genes. After they tried to steal DNA from the Enterprise crew, Dr. Pulaski persuaded them to accept the Bringloidi as fellow settlers so the colony could have children naturally.