Biology by Matthew Distefano

Author:Matthew Distefano
Language: eng
Format: epub
Publisher: Career Press
Published: 2011-12-14T16:00:00+00:00

An important concept to understand is that two organisms cannot occupy the same niche at the same time. If two organisms do occupy the same niche, competition results and only one organism will eventually remain in that particular niche. The other organism must then be able to move to a different niche in the environment or perish.

As Darwin noted in his theory of evolution, organisms are always competing for available food and shelter within an environment. Competition will happen any time organisms require the same food and/or shelters but there is not enough food and/or shelter for all organisms present in the ecosystem. For example, a fish-eating eagle will compete with other fish-eating eagles for food when the fish supply in a region is low. Two small plants growing close to one another will compete for light on the forest floor if the amount of light reaching the ground is limited to one spot.

Other forms of organism interaction can occur in an ecosystem besides competition. It is also true that sometimes an organism will benefit from something another organism does within an ecosystem. Symbiosis is an interaction among two species within an environment where at least one species obtains a biological advantage because of this interaction. There are three basic types of symbiotic relationships witnessed in any ecosystem:

1. Mutualism is an interaction among two species where both species benefit from the relationship. The bacteria that live in the large intestines of humans are an example of this type of relationship. These bacteria receive food and shelter within the wall of the intestines, while at the same time they produce a vitamin needed by humans.

2. Commensalism is an interaction between two species where only one species benefits from the interaction. The species that does not benefit from this interaction is unaffected. An example of this type of relationship would be the remora fish that swims underneath the belly of a shark. The remora feeds on scraps of food not eaten by the shark during feeding, while the shark is unaffected by the presence of the remora fish.

3. Parasitism is an interaction between two species of organisms where one organism obtains a benefit and the other organism is harmed by the relationship. A dog flea is an example of parasitism. The flea feeds on the blood of the dog and obtains shelter in the hairs of the dog, while the dog is harmed by the loss of blood and possible infections or diseases that can result from the feeding of the flea.

Do not confuse parasitism with predation. Predation is when one organism kills and eats another organism for food. A lion feeding on a zebra is an example of predation. The lion would be considered the predator and the zebra would be considered the prey in this particular example of predation. This type of relationship among organisms will be looked at a bit more closely in Lesson 6-6.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.