Introduction to Ecology Biology A/Ecology

What is Ecology?  Ecology is the scientific study of how organisms interact with each other and their environment.

Energy Flow  All organisms require energy from their environment to function.  Sunlight is the main source of this energy

Autotroph vs. Heterotroph  Autotrophs are organisms that can use energy directly from sunlight or chemicals to produce their own food. –Autotrophs are also called producers. –Examples: Plants and algae  Heterotrophs are organisms that get energy from the food they eat. –Heterotrophs are also called consumers.

Decomposers  Decomposers are a special type of heterotroph: –Decomposers break down organic matter

Food Chains  Energy flows through an ecosystem from producers to consumers.  Food chains show this one-way flow of energy:

Food Webs  In most ecosystems many food chains interact together.  Food webs link all the food chains in an ecosystem together:

Energy Transfer  When energy flows from one organism to another, only about 10% of the energy gets transferred.  This is because each organism uses some energy for itself.

Energy Transfer Continued  Therefore, the more transfers that occur, the less energy is available for the organism at the top of the food chain. –For example, 10% of the sun energy captured by the grass gets passed along to the mouse that eats it. Only 10% of that energy gets passed along to the snake that eats the mouse.

Energy Pyramids  Energy Pyramids describe the transfer of energy from one level of the food chain to the next:

Ecosystem Vocabulary  An ecosystem is all the organisms living in a particular place, along with the non-living environment. –Example: grass, mice, snakes and hawks live in a very dry and hot prairie with frequent fires and little rain.

Biotic vs. Abiotic  Biotic factors are the living parts of an ecosystem –Examples: grass, mice, snakes and hawks  Abiotic factors are the non-living parts of an ecosystem –Examples: Frequent fires, high temperatures, drought.