An increase in food and a decrease in predators would most genetic variation in a population

An increase in food and a decrease in predators would most likely INCREASE genetic variation in a population.

An increase in food and a decrease in predators would most likely increase genetic variation in a population because say for ex there are wolves and rabbits, if all the wolves are gone, and only rabbits with more food to eat, of course the rabbits will increase since there are no predators to eat them or eat their food either.

Other organisms can change their behavior to take the place of the plants in the ecosystem.