Track and field will introduce mandatory DNA sex testing for athletes entering female competitions, its global leader said Tuesday, making it the first Olympic sport to add the requirement. The move comes amid an increasingly vexed debate over eligibility rules in female sports and comes less than a year after the issue erupted at the Paris Olympics when questions about the qualifications of two women who went on to secure gold medals in boxing led to tumultuous — and at times disturbing — scenes inside and outside of the ring. The move is essential to protect female sports, said Sebastian Coe of Britain, the head of track’s governing body, World Athletics, and a former double Olympic gold medalist in the 1500 meters. He said the new policy, which will subject competitors to what is described as a noninvasive cheek swab or dry blood DNA test, was part of his vow to “doggedly protect the female category and do whatever it takes to protect it.” World Athletics said the new tests could be in place in time for its next world championships, in Tokyo in September.