Middle School Life Science: Introduction to Ecology - Communities — Flashcards

Predation is a relationship in which members of one species consume members of another species. The consuming species is called the predator. The species that is consumed is called the prey. For examples, wolves are predators, and moose are their prey.    
A predator-prey relationship tends to keep the populations of both species in balance. As the prey population increases, there is more food for the predators. So after a slight lag time, the predator population also increases. As the number of predators increases, more prey animals are consumed. This causes the prey population to decrease, followed by the predator population decreasing again.    
Some predator species play a special role in their community. They are called keystone species. When the population size of a keystone species changes, the populations of many other species are affected. Prairie dogs are an example of a keystone species. Their numbers affect most of the other species in their community. Prairie dog actions improve the quality of soil and amount of water for plants, upon which most other species in the community depend.    
Both predators and prey have adaptations to predation that evolve through natural selection. Predator adaptations help them capture prey. Prey adaptations help them avoid predators. A common adaptation in both predator and prey species is camouflage.