Transcript niches - Cloudfront.net

Ecosystems & Living Organisms:
Interactions and Niches
Biological Communities
• Lack defined boundaries  orgs never
isolated
• Intrxns. lead to creation of ecological nichesEach org. has a role in an ecosystem.
Competitive Exclusion
• Two species with similar
requirements cannot occupy the
same niche (Gause’s Law)
P. caudatum
P. aurelia
Logistic Growth
Keystone Species
• Key members of community
– Critical elements
– NOT always most abundant
– ALWAYS most important
• KEY to conservation efforts
What is Predation?
• Members of a predator species prey on
members of a prey species
Stephen Colbert: Snakes and Hamsters
•• http://www.colbertnation.com/the-colbert-reporthttp://www.comedycentral.com/motherload
videos/58446/january-31-2006/craziest-f--king-thing-i-ve/index.jhtml?ml_video=58446
ever-heard---snake-and-hamster
Predator Strategies
Structural
• Natural Weapons: Fangs, claws
• Flexible bodies and Larger Size
Sharp Talons!!
Predator Strategies
• Ambush Techniques:
Stalk a victim, Gape &
Suck (fish), Keen
eyesight, Venom
Prey Strategies
Defense Techniques: Inflate, Flee,
Fight Back, Stab, Poison
Prey Strategies
Structural advantages: Hard
Body, Thorns/Spines, Break
away body parts, Nat. Weapons
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
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
Interactions Among Organisms
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
Endoparasites
• Parasites that live within the body of the
host!
• Ex. Tapeworm…
Ectoparasites
• Parasites that feed on the external
surface of the host.
• Ex: ticks
Intraspecific Competition
• Between SAME species
Interspecific Competition
• Competition between
DIFFERENT species
Intra or Interspecific Competition??
• http://www.youtube.com/watch?v=Tt6C6P
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