ORGANISMS AND THEIR ENVIRONMENT

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