An ecologist is studying the effects that a population of predators is having on a population of prey. He used data from the field to produce this line graph. Which conclusion can you draw from the graph?

A.

There is no relationship between the population of predators and prey.

B.

The population of prey decreases with a decrease in the population of predators.

C.

The population of prey increases with an increase in the population of predators.

D.

The population of prey decreases with an increase in the population of predators.

The correct answer is - D. The population of prey decreases with an increase in the population of predators.

The predators have a very important ecological role, to regulate the number of the prey animals, or rather of the herbivores. The predators are carnivores, which means they eat meat to survive, thus kill other animals to get food. By having an increased number of predators, the population of the prey animals decreases. The reason for that is that the predators need to kill the prey animals, and as their numbers grow, they will kill more and more animals of prey. That will lead to a decrease in the population of the prey animals, but also make a balance in the environment between the plants, the prey animals, and the predators, a balance that will enable all of them to exist and function properly.