Predation is a relationship in which members of one species (the predator) consume members of another species (the prey). The lionesses and zebra in the Figure below are classic examples of predators and prey. In addition to the lionesses, there is another predator in this image. Can you spot it? The other predator is the zebra. Like the lionesses, it consumes prey species, in this case, grass species. However, unlike the lionesses, the zebra does not kill its prey. Predator-prey relationships such as these account for most energy transfers in food chains and food webs. A predator-prey relationship tends to keep the populations of both species in balance.
Predator-Prey Population Dynamics. As the prey population increases, why does the predator population also increase? In the predator-prey example, one factor limits the growth of the other factor. As the prey population deceases, the predator population is begins to decrease as well. The prey population is a limiting factor. A limiting factor limits the growth or development of an organism, population, or process.
Predation and Population A predator-prey relationship tends to keep the populations of both species in balance. This is shown by the graph in Figure below. As the prey population increases, there is more food for predators. So, after a slight lag, the predator population increases as well. As the number of predators increases, more prey are captured. As a result, the prey population starts to decrease. What happens to the predator population then?
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Remember there are two types of competition. Multiple lions going after the same zebra is intraspecific competition.
The population eventually reaches a carrying capacity, which is the population size that can be sustained over time in a given environment. The carrying capacity varies population to population and can also change over time as the environment changes. In nature, populations often overshoot and then undershoot the carrying capacity before eventually stabilizing at the carrying capacity.
