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 species 3 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