Factors that Shape Ecosystems

Symbiosis, Succession, and Invasive Species

Factors that Shape Ecosystems• Ecosystems are shaped by a

combination of biological and physical factors

Abiotic Factors• non-living parts of an ecosystem

Biotic Factors• living parts in an ecosystem

Factors that Shape Ecosystems• Together, biotic and abiotic factors

determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives.

Habitat• the area in which an organism lives

Niche• role or occupation that an organism plays in

its community (habitat)

Community Interactions• contact between organisms that

help shape ecosystems

Community Interactions• Competition• Predation• Symbiosis

–Mutualism–Parasitism–Commensalism

Competition• occurs when members of two or

more species populations rely on the same resource for survival

Competition Exclusion Principle• no two species can occupy the same niche

in the same habitat at the same time– there are winners and losers

Predation• a relationship (usually) between

two species in which one is killed (for food) and the other benefits

Symbiosis• specific relationships that occur between

two different species

Symbiosis• Mutualism• Parasitism• Commensalism

Symbiosis: Mutualism• a specific relationship between two

organisms/species in which both benefit

Symbiosis: Parasitism• a specific relationship between two

organisms/species in which one benefits and other is harmed

Symbiosis: Commensalism• a specific relationship between two

organisms/species in which one organism benefits and the other is unharmed

Symbiosis: Commensalism– rare

• most relationships are at least slightly mutualistic or parasitic

Succession• the process by which an ecosystem slowly

returns to its original state after some disturbance– species replace species as succession

progresses– lead by a pioneer species

Succession

Succession

Pioneer Species• a species that establishes an ecosystem

after it has been severely changed/altered• this organism 'paves' the way for other

species to return to the ecosystem

Succession

Pioneer Species• a species that establishes an ecosystem

after it has been severely changed/altered• this organism 'paves' the way for other

species to return to the ecosystem– Typically plants return to an ecosystem before

animals

Succession

Pioneer Species• a species that establishes an ecosystem

after it has been severely changed/altered• this organism 'paves' the way for other

species to return to the ecosystem– Typically plants return to an ecosystem before

animals– Usually small organisms (grasses, insects, etc.)

Invasive Species• an introduced species that negatively

affects the ecosystems they invade financially and/or ecologically– also called "non-indigenous" or "non-native"– cost people money and/or threaten native

species– can be plants or animals

Invasive Species