The Biosphere= any part of the earth which supports living
things– Includes land, water, and soil– Consists of biotic (living) things and abiotic
(non-living) things• Biotic factors: plants, other animals, fungi,
bacteria, etc.• Abiotic factors: air temperature, length of day and
night, soil quality, amount of rainfall, etc.
Ecological Levels of Organization
• Individual Organism – Each organism has a habitat where it lives out its life
• Example: a lawn, a pond, a grove of pine trees• Size of habitat varies for different species
– Several different species can share a habitat• Example: a pond contains many different species of fish, plus
bugs, plants, bacteria, etc.
– Each species occupies a niche in the habitat—how it lives, what it eats, etc.
• No 2 species can occupy the same niche in the same habitat
• Population = group of organisms, all the same species, living in a particular area at the same time– Example: we can talk about the elk population in
Rocky Mountain National Park
• Community = several interacting populations living together in an area– Example: the forest community in RMNP, which
includes elk, deer, bears, many different plants, etc.
• Ecosystem = community and the abiotic factors– example: the forest community and the climate,
temperature, pollution, wind, etc.
• Biosphere
Symbiosis= a close, permanent relationship between 2
different species3 kinds: mutualism, commensalism and parasitism• Mutualism = symbiotic relationship in which
both species benefit– Example: lichen, which is a combination of an algae
and a fungus• fungus is “fed” by food made by the algae, which can do
photosynthesis• Algae benefits because the fungus is better able to find and
soak up water
– Example: cleaner wrasse lives on other fish
• Fish gets cleaned by the wrasse
• Wrasse gets food from whatever it can scavenge
– Example: E. coli which lives in your gut
• E. coli breaks down your food for you
• E. coli gets a lot of nutrients from your food
• Commensalism = one species benefits, the other is neither helped nor harmed– Example: birds that ride on cows’ backs
• Birds get food to eat when the cow walks and stirs up insects• Cow doesn’t care—it doesn’t get anything back from the bird
at all
• Parasitism = parasite harms, but does not kill, the host; parasite benefits, host is harmed– Example: tapeworm which lives in intestines
of animals• Tapeworm eats your food and harms you
– Example: brown-headed cowbird is a “nest parasite”
• Lays eggs in nests of songbirds so the other birds will raise their young for them
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