A microscopic image of a ciliate Credit: B. Sonntag |
The classic predator-prey model
Individuals of the same species who live and reproduce together in a relatively enclosed area form a population. The size of this population can be subject to gentle or extreme fluctuations, due to various environmental influences. This decrease and increase in individuals over time is called population dynamics.
Population dynamics are often explained in terms of purely ecological processes, as can be seen in the example of predator-prey relationships. Here, population dynamics are primarily determined by prey growth rates and predator feeding rates.
Classical predator-prey models assume that prey organisms evolve unaffected until a predator arrives and decimates the prey. Predators find abundant food and also become more abundant. Increased predation pressure reduces prey densities, which causes predator densities to decrease until prey recovers. Thus, when prey is depleted by the predator, an overall population collapse occurs. This model only represents ecological dynamics. However, predator-prey relationships are also an important cause of evolutionary adaptation.