From what I know this could be wrong, but in the four stages of natural selection, the first step is overproduction, the second step is adaptation, and the third step is competition or survival of the fittest. This means that only the organisms with the best adaptations for their surroundings will survive. COULD BE WRONG SORRY IF IT IS
This is apoptosis. in reference to sunburn, this is when cells die in order to protect you and your skin from damaged skin DNA (possibly cancer causing).
