How biotic factors regulate the population of animals in an ecosystem.


        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;



        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;



        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;