Transcript What Shapes an Ecosystem?

What Shapes an Ecosystem?
4.2
Biotic vs. Abiotic Factors
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Biotic Examples
Trees
Grasses
Weeds
Birds
Snakes
Fish
Bacteria
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Abiotic Examples
Temperature
Precipitation
Nutrient
Dirt
Rock
Humidity
Sunlight
Habitat vs. Niche
 Niche
 Habitat
 Includes habitat AND
 Organism address
place in the food web
only!
 How the organism
lives and uses the
 Contains abiotic and
physical and
biotic factors directly
biological conditions
affecting the organism
 What it eats, how it
gets food, interactions,
reproduction, etc.
Can any 2 species occupy the
same niche?
 NO! See the warbler example For many years it was thought that 5 species of
warblers occupied the same niche. Robert
MacArthur set out to learn more. As the rule of
competitive exclusion goes:
 two species with essentially the same niche
cannot coexist because one will always outcompete and displace the other.
How did he do this?
 “By measuring distances down from the top and
outward from the trunk of individual spruce, fir, and
pine trees, MacArthur divided the trees into zones and
recorded feeding positions of the different warblers
within each. A record in zone "T3" indicated a bird
feeding among the abundant new needles and buds of
the tip of a branch, between 20 and 30 feet from the
top of the tree. A record of "M3" signified feeding
mostly among dead needles at the same height but in
the middle zone of a branch. A record of "B2"
represented a warbler feeding on the bare, lichencovered base of a branch. In all, 16 different positions
were distinguished”
MacArthur’s Results
 MacArthur found that each warbler
species divided its time differently among
various parts of the tree and can eat a
variety of different foods(shown below).
Types of Symbiotic Interactions
 Symbiosis: Any relationship in which 2
species live closely together
 Ex: Imperial Shrimp and Sea Cucumber
(hitches a ride!), Cuckoo Bird (lays eggs in
other birds nests!)
Predation
 One organism captures and feeds another
organism
 Ex:Lynx and the Hare
“Run bunny, run!”
Mutualism
 both species benefit
 Ex: Honeyguide and
Honeybadger, Acacia
Tree and Stinging Ants,
Oxpecker and Rhino,
Cleaner Fish
Honey Guide and Honey
Badger
Acacia and Ants
Oxpecker/
Rhino
Commensalism
 one species benefits, the other is neither
helped nor harmed
 Ex: Sm. Pilot Fish and Shark, Barnacle and
Whale, Remora and Turtle, Grouse and
Antelope
 http://www.fotosearch.com/ATB717/vus118/
Commensalism-Remoras
http://www.oceanfootage.com/stockfootage/Sea_Turtle/owner
%3Dhowardhall
Barnacles and Humpbacks
Parasitism
 one species lives on or in another organism
and harms it
 Ex: Parasitic Fungi feeding on jungle insects,
Tapeworm, Ringworm
Tapeworm (yuk!)
Parasitic Jungle Fungi
Ecological Succession
 Series of predictable changes in a community
over time
 Usually old die out and new replaces
 Causes include gradual climate change
(global warming?) or sudden disturbance
(volcanic eruption, forest fire, humans
clearing forests)
Land Succession
 Primary Succession: occurs only where no soil
exists (possibly from volcanic eruption)
 LichensMossesGrassesTree Seedlings
and Shrubs take root
 Which species is the “pioneer species”?
 What makes it successful in rocky terrain?
 What animals can primary succession attract?
 Do the animals change with the plant life?
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http://bcs.whfreeman.com/thelifewire/content/chp55/55020.html
Secondary Succession
 Occurs after a disturbance like forest fire
where soil already existed
 Returns ecosystem to natural state
 “Climax Community” term given by
ecologists to the stable ecosystem/end
product
 Do all ecosystems recover after natural
disasters or human interactions?
Mt. St. Helens, May
th
17
1980
4 Months After Eruption
4 Years After Eruption
Marine Succession
Occurs within an already stable environment!
1. Whale carcass sinks to bottom of ocean and
attracts scavengers and decomposers (sharks,
hagfish, and tiny amphipods)
2. With most tissue gone, scavengers leave and are
replaced with small fish, crabs, and snails
3. With only bone left, it seems barren. BUT,
heterotrophic bacteria break down oils in whale
bones (which creates energy for chemosynthetic
bacteria to begin a whole new food chain!)