Niches & Community
Interactions
BIOLOGY
Warm Up
• On the whiteboard to the left, calculate
the amount of energy at the producer, 1st
consumer, 2nd consumer, 4th consumer,
and 5th consumer level.
• What does the amount of energy at the
top consumer level tell you about the
number of large carnivores?
Niche and Habitat
• Niche: An organism’s role in the ecosystem
(&food chain/food web)
• Habitat: Physical place where an organism
lives
Competitive Exclusion Principle
• States that no two species can occupy exactly
the same niche in exactly the same habitat at
exactly the same time.
• Why??
Biotic & Abiotic Factors
• Biological components of an ecosystem are called biotic
factors. Examples?
• Animals, plants, mushrooms, bacteria..
• Physical components of an ecosystem are called abiotic
factors. Examples?
• Sunlight, heat, precipitation, humidity, soil type,…
How do these factors influence in each other?
• A keystone species is a species that has an unusually
large effect on its ecosystem.
Why are they called a “Keystone” species?
• Keystone species form and maintain a
complex web of life.
creation of
wetland
ecosystem
increased waterfowl
Population
keystone species
increased fish
population
nesting sites
for birds
Keystone Species
• How might the grey wolf be a
keystone species?
• What about the honeybee?
Symbiosis: any relationship in which 2 species live
closely together
• 1. Mutualism
-Both benefit
• 2. Parasitism
-One benefits, other is harmed
• 3. Commensalism
-One benefits, other is neither
helped nor harmed
Symbiosis
Parasitism versus Predation
• Predation: Predator kills prey instantly
Predator normally much larger than prey
• Parasitism: Parasite kills prey slowly or not at
all
Parasite normally smaller than prey
Exit Slip (on your own)
• Do you think humans are in a symbiotic
relationship with any other organisms?
1) Name one, and 2) EXPLAIN which type of
symbiotic relationship it is & why.
Warm Up:
• What’s the difference between niche & habitat?
• Where did “keystone species” get its name?
• What form of symbiotic relationship is the following:
• Vulture & Lion
•
Crocodile & Bird
Cuckoo bird & other birds
Do Cats Make you Crazy?
Toxoplasma Virus
Can only reproduce inside cats
Make rats more trusting and
attracted to cat smell
“Groundbreaking research showed that infected
men tend to be more suspicious, withdrawn, and
prone to breaking rules, while infected women
are more trusting, outgoing, and law-abiding.”
Competitive Exclusion Principle
• What happens to the “losers”?
• Adaptation & finding a new niche?