Ecological Relationships in Nature: Populations

A population is a group of individuals of the same species living together in the same habitat at any given time. Many organisms live in populations for the reasons that it is safer when there are more of them, it is easier to find a mate, and food and shelter may be abundant in the habitat, bringing the organisms to live in that habitat, subsequently making them live with each other.

Biologists study populations for many reasons. They can find out what factors affect populations, they help in the conservation of endangered animals, or even warn against killing certain animals who are starting to become endangered. The size of the population is affected by these factors:

1. Competition
2. Predation
3. Parasitism

Competition is when two or more organisms 'fight' or 'compete' each other for the same resource. For example, plants could compete for sunlight, food, and soil. Animals could compete for mates, territory or food. A shortage of a needed resource could increase the competition between organisms, and some of the losers may even starve to death if the resource is food. There are two recognised types of competition. There is contest competition and scramble competition. Contest competition is when a physical fight or confrontation is involved. Deer do this by locking their antlers together and pushing, and the one who gives in is the loser. Scramble competition is when each organism competing tries to gather the most of the resource available for itself. For example, birds do this during spring when they have chicks to feed. The parents try collecting as much as possible food before other parents do.

Predation is when an organism kills another organism for food. The predator, the killer, has many tricks up it's sleeves (called adaptations) to capture the prey, the victim. For example, the cheetah has a lot of speed to capture it's prey, and it's spotty coat camouflages in it's environment. They can have good eyesight, good hearing, or even the perfect teeth for biting and chewing the sort of food they capture. Some predators hunt in groups, and some migrate to another area where food is more bountiful, where as other predators would simply change their diet. Preys also have adaptations to protect themselves. Some plants use thorns and spikes to ward off predators.

Some animals use a camouflage colour, and others use a warning colour. A warning colour is a bright colour, sometimes red, used to ward off predators because the bright, vivid colour is usually associated with bad taste. Some preys even actually have a bad taste.

Parasitism is when an organism is living in or on another organism. There are two types of parasites: endoparasites and ectoparasites. Endoparasites live inside their host, for example, roundworms. Ectoparasites live on the outside, or on the surface of their host, such as fleas, or lice. Parasites don't generally kill their hosts unless the parasites have finished their life cycle.

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