1. Ecology
Definition: the scientific study of interactions among organisms and their environment
Branch of biology that was developed from natural history
Study reveals the relationships between living and non-living parts of the world

2. Ecology Abiotic Biotic:
The environment is divided into living and non living parts:
Abiotic
Physical factor such as: air, temperature, moisture, soil, light
These factors make up an organism’s habitat
Habitat: the area where an organism lives
Biotic:
All living or once living components of an ecosystem
Includes dead organisms and the waste of organisms

3. Levels of Organization in Ecology
To help ecologists understand the interactions of the biotic and abiotic parts of the world, scientists have organized the living world into levels:
Biosphere
Ecosystem
Community
Population
Organism

4. Levels of Organization
Biosphere
The part of the Earth’s covering where life is possible
Goes from the top of the atmosphere to the bottom of the ocean; about 12 miles high!
Supports a wide variety of organisms
If the earth were shrunk to apple size, the biosphere would be thinner than the apple skin

5. Levels of Organization
Ecosystem
A community of organisms and their living and non living surrounds
Living components of an ecosystem are the biotic factors
Non living components of an ecosystem are the abiotic factors

6. Levels of Organization
Community
A group of various species that live in the same habitat and interact with each other
Population
group of organisms of one species that interbreed and live in the same place at the same time
Organism
living member of species

7. Levels of Organization
In a desert…..
Organism: coyote
Population: pack of coyotes
Community: pack of coyotes, hawks, owls, snakes, scorpions, & reptiles
Ecosystem: populations of animals listed above, cacti, shrubs, sand dunes, climate, rocks, temperature
Biosphere: the earth

8. Biodiversity Includes: The variety of organisms within a given area
The genetic variation within a population
The variety of species in a community
The variety of communities in an ecosystem
Both abiotic and biotic factors help to determine the biodiversity of an area

9. In an Ecosystem Habitat: a place where an organism lives out its life
Niche: the specific role and position a species has in its environment.
Organisms may share parts of their niche, but never the whole thing!

10. In an Ecosystem
Fundamental Niche: the entire range of conditions where a species can survive
Shaped by competition for resources between species
Realized Niche: the actual niche that an organism occupies within an ecosystem
The establishment of a niche allows for several organisms to live in the same habitat while reducing competition for resources!!

11. Changes in an Ecosystem
Succession: the replacement of one community by another at a single location over a period of time
First organisms to appear are pioneer organisms
Primary Succession occurs after natural disasters
Volcanic eruptions, fires, hurricanes, tornadoes, etc
Secondary Succession occurs after HUMAN involvement
Clearing of land for development, clear cutting the forest, etc

12. Relationships in an Ecosystem
Symbiosis
Two species live in close association with each other. Can be positive or negative
Mutualism: both species benefit
Ex: cleaner shrimp/fish
Commensalism: one species benefits, the other does not, but is not harmed
Ex: orchids growing on trees
Parasitism: one species is helped while the other is hurt
Ex: Ticks on a dog.
The tick is the parasite and the dog is the host