• Symbiosis - a relationship in which two organisms of different species 'live together' for a period of time
• Parasitism - a form of symbiosis in which one organism derives nutrients from the second organism which suffers some harm but is usually not killed (e.g. A tick is the parasite that feeds off a dog which is the host.)
• Mutualism - a form of symbiosis in which both organisms help each other (e.g. A remora fish eats the algae and barnacles from the skin of a shark which, in turn, protects the remora.)
• Commensalism - a form of symbiosis in which one organism helps the other organism, but there is no benefit nor harm done in return (e.g. A clown fish lives inside a sea anemone and is protected by it. The sea anemone derives no benefit nor harm from the relationship.)
• Predator / Prey Relationships - the relationship in which one organism (predator) hunts and eats another (prey) (e.g. lion / antelope)
• Competition - a relationship where two types of organisms compete for the same resource such as food, water, nesting site (e.g. sheep and kangaroos compete for grass)
• Understanding the interaction of the biotic and abiotic factors in an ecosystem can help us to see why particular human activities may be a problem for human survival.
• Example: The loss of ozone in the stratosphere increases the quantity of UV radiation on the surface of the planet. In the same way that humans experience sunburn from too much sun exposure, so do plants. Excessive UV may damage or destroy plant protein and DNA, killing the plant.
• Plants and animals interact with their abiotic environment. Attempts are made by the plant or animal to reduce or increase the quantity of an abiotic factor.
1. Aspens have a waxy coating on their bark to reduce the quantity of sunlight absorbed.
2. Desert plants have hair-like structures to reduce the quantity of sunlight reaching the leaf surface.
3. Pine trees have needle-like leaves that reduce the quantity of heat lost during the winter.
• Understanding the interaction of the biotic and abiotic factors in an ecosystem can help us to see why particular human activities may be a problem for human survival.
• Example: The loss of ozone in the stratosphere increases the quantity of UV radiation on the surface of the planet. In the same way that humans experience sunburn from too much sun exposure, so do plants. Excessive UV may damage or destroy plant protein and DNA, killing the plant.
• Plants and animals interact with their abiotic environment. Attempts are made by the plant or animal to reduce or increase the quantity of an abiotic factor.
1. Aspens have a waxy coating on their bark to reduce the quantity of sunlight absorbed.
2. Desert plants have hair-like structures to reduce the quantity of sunlight reaching the leaf surface.
3. Pine trees have needle-like leaves that reduce the quantity of heat lost during the winter.
Fig. 1 Ecosystems are not isolated from one another. One ecosystem blends into the next through a transitional region, an ecotone, which contains many species common to the two adjacent systems.
Fig. 2 An ecotone may create a unique habitat with specialized species not found in either of the ecosystems bordering it.
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