How biotic factors regulate the population of animals in an ecosystem.
Predation;
i. In the absence of predators, the prey population increases rapidly; this may exceed carrying capacity leading to environmental degradation;
ii. The presence of predators prevents rapid population growth as they eat some of the prey;
iii. As the numbers of prey increases also the predator population increases due to availability of food;
Parasitism;
i. Parasite usually obtain food and shelter from the host;
ii. Parasites weaken the host, lowering their fertility, hence making them unable to reproduce;
iii. They make the host vulnerable to environmental factors like diseases hence reducing the population;
iv. Some parasites may kill the host thus reducing the population;
Competition;
i. Animals compete for food; mates; and space;
ii. When resources are available, the population growth increases rapidly due to less competition;
iii. When resource are scarce less adapted organisms are out competed hence may die; or migrate hence reducing the population;
Human activities;
i. Man has imported / exported new animals to new areas increasing/ decreasing the population;
ii. Environmental conservation through afforestation and reafforestation may lead to increase in population of some animals;
iii. Man has destroyed vegetation by deforestation affecting negatively on the numbers of some animals depending on forests as their habitats;
iv. Protection of endangered species likely to face extinction have been artificially raised causing an increase in population;
v. Some human activities eg use of pesticides, agrochemicals and acaricides have caused pollution; decreasing the population of other animals; killing of animals though poaching / hunting / fishing reduce their population;