Ecology

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. 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 Ecology The environment is divided into living and nonliving parts:

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