Check all statements below that are true. All organisms must compete for survival. When organisms struggle to survive, they usually mutate to increase chances of reproduction. Some organisms have phenotypes that make them better competitors than others in their environment. Animals undergo natural selection, but plants and other organisms generally do not. Natural selection continues to occur even today. Phenotypes found in the most successful members of a species become the most prevalent after several generations. A decrease in food availability will increase the variation in a population.