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What shapes an
ecosystem?
TSW identify and describe
interactions between individuals in
a community
Biotic & Abiotic Factors
Biotic: Living
 Abiotic: Non-living
 Can you think of any
examples?

What is a niche?
Def: The full range of physical &
biological conditions in which an organism
lives & the way in which an organism uses
those conditions
 An organism’s occupation
 Includes place in the food web, range of
survivable temps, type of food eaten,
physical conditions needed for survival…

What determines the # of niches in
an ecosystem?

The combination of
biotic and abiotic
factors in an
ecosystem
Key Points
No two species can share the same niche
in the same habitat (COMPETITIVE
EXCLUSION PRINCIPLE)
 Different species can occupy niches that
are similar

Competition
Organisms of the
same or different
species attempt to
use an ecological
resource in the same
place at the same
time
 Usually results in a
winner & a loser

Predation

One organism captures & feeds on
another organism
Symbiosis
Relationship where any 2 species live
closely together
 3 Main Types

– Mutualism
– Commensalism
– Parasitism
Mutualism
Both species
benefit from the
relationship
 (+, +)
 Example:
Flowers/Insects

Commensalism
One member of the
association benefits,
while the other is
nether helped, nor
harmed
 (+, +/-)
 Example:
Barnacles/Manatees

Parasitism
One organism lives on or in another
organism causing it harm
 The parasite obtains all or some of its
nutritional needs from the host
 Example: Fleas, ticks, lice/ Mammals

Ecological Succession

The series of predictable changes that
occurs in a community over time
1º Succession

On land, succession that occurs on
surfaces where no soil exists
2º Succession

Occurs when a disturbance of some kind
changes an existing community without
removing the soil
Pioneer--------- Climax
Community
The 1st set of species
to move into an area
after a disrupting
event
 Example: Corals
moving onto a sunken
ship

Mature, stable
community (can still
undergo changes)
 Example: Volcanic
wasteland turning
into a rainforest
