Download Who Lives Where?

Community Ecology
Big Idea 4: Biological
Systems Interact
ECOLOGY
• Study of
living
organisms
and their
interactions
with the non/
living
environment
Who Lives Where?
• Orgs adapted to a specific set
environmental conditions, through
evolution (natural selection)
Peppered Moths of
England
Who Lives Where?
•
Dispersal:
Movement of
species from areas
of high pop.
density to low.
• Can be caused by:
1. Species expanded
range naturally
2. Species was
transplanted
Great tailed grackle: Moved
north to Gulf of Mexico
Who Lives Where?
• Abiotic and Biotic
Factors are Limiting!!
• Abiotic: temp., H2O,
sun, wind, soil,
climate.
• Biotic: animals, plants,
bacteria
Ex: Tidepools in Intertidal Zones,
Must withstand exposure to sun at
low tide.
Biological Communities
• An area where different pops interact w/
each other w/ no boundaries
• Leads to creation of ecological nichesa role in an ecosystem (fills a niche).
What’s
My
Niche?
Communities Have Competition…
• Interspecific Competition: occurs b/t
diff. species.
• Due to resources in short supply.
Intraspecific
Competition
Intra or Interspecific Competition?
Competitive Exclusion
• 2 species cannot coexist in
a community if their niches
are identical. (Gause’s Law)
Paramecium caudatum
Paramecium aurelia
Gause’s Experiment
Logistic Growth
When Niches are the Same…
• Species can
evolve to
coexist
• Resource
partitioning- a
species
changes
behavior so it
can coexist w/ a
similar species.
Resource Partitioning
Keystone Species
• Key members of community
– Critical elements
– NOT always most abundant
– ALWAYS most important
• KEY to conservation efforts
Predation in Communities
• Members of a predator species prey on
members of a prey species
Predator Strategies
• Stalking, Keen eyes, Venom
• Natural Weapons: Fangs, claws
• Flexible bodies and Larger Size
Prey Strategies
Defense Techniques: Inflate, Flee,
Fight Back, Stab, Poison
Mimicry
• Batesian mimicry: a
harmless species
looks like a harmful
species
• Mullerian mimicry:
2 harmful species
look like each other
Cuckoo Bee
Yellow jacket
Scarlet King Snake
Coral Snake
Predation Feedback Systems
• Positive feedback (outcome is +) for predator
• gets to eat prey, can reproduce…
• Negative feedback (outcome is -) =
• prey population falls, no food, decrease in
predator population
Herbivory
• Herbivore only eats a part of
plant/alga.
• Plants may have chemicals to deter
Symbioses in Communities
Symbiosis:
relationship b/t
2 species
•Mutualism (+,+)
•Commensalism
(+,0)
•Parasitism (+,-)
Mutualism
• Both Species Benefit
• Rhinos and oxpeckers
• Symbiotic fungus
found on plant
roots
• Aids in water
retention, mineral
uptake (nitrates)
W/out M
With M
Mycorrhizae
Commensalism
• One member is helped, the other
neither benefits or is harmed
• Cows and Cattle Egrets
Parasitism
• + and relationship
• parasite benefits,
host loses
• parasite usually
smaller than host
Leech Bite, Thailand
Lamprey