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What happens when 2 niches overlap?
how species interact
Environmental Science 302
Problem:
2 niches overlap
WHAT IS YOUR SOLUTION?
1. Migrate
2. Change feeding habits
3. Adapt behavior
4. Suffer a sharp population decline
5. Become extinct in that area
What type of species overcome this more easily?
 Generalists
 or Specialists?
Phrased another way:
I want something that you want…
• Will we compete?
• Will I eat you?
• Will we work together
some how?
• In nature, there are 3
basic types of
interactions…
Competition
Predation
Symbiosis
Interaction
Competition
+
-
0
Predation
Mutualism
Parasitism
Commensalism
Interacting
Examples
I. Competition
INTERFERENCE
• Species A limits Species B’s
access
EXPLOITATION
• A & B have equal access but
differ in how fast or
efficiently they exploit it
• Aka: establishing a territory
• Ex: invasive species
II. Predation
• The prey does not have to die!
– Can eat all or part
• Predation is not only about carnivores!
• Can be GOOD for prey population
because…
 drives natural selection!
– Sick, weak, & aged die, leaving resources
for the healthy
Remember this????
• A trophic level is
an organism’s
feeding level.
• What trophic level
is the organism on
your card?
Can you make a food chain with
all the cards at your table?
• Draw the food chain in your
book.
• Remember what two things you
always need!
Everything’s connected!
What happens if you
spray a pesticide to
kill the mosquitos?
Owl Pellets
• What are they?
1. Using forceps, probes, and toothpicks dissect the owl
pellet.
2. Sort the bones onto the chart.
3. Draw a diagram of a food web (of at least 5 organisms)
with the owl at the uppermost trophic level.
Capturing Prey
• Herbivores got it easy!
– Special digestive adaptations
• EX?
• Carnivores must hunt!
– Predator needs MOBILITY, SENSES, and ABILITY
TO HANDLE prey
• EX?
Prey Escape & Defense
• RUN!!!
• Physical Defenses
– Structure
– Crypsis
– Warning Coloration
• Chemical Defenses
• Deception
– Looks
– Behavior
• Behavioral
– Scare tactics
• Loss & Regeneration
Prey
adaptation
Synchlora larvae
Wavy-lined Emerald Caterpillar
III. Symbiosis
• “Living together” in a long-lasting relationship
3 types
Parasitism
Mutualism
Commensalism
Parasitism
1 species (PARASITE) gets nourishment by living on,
in, or near another species (HOST) over an
extended period of time
– Endoparasites
– Ectoparasites
Rarely Lethal!
Why would you kill a good thing?
Mutualism
• Both species benefit in various ways
– Having pollen dispersed for reproduction
– Being supplied with food
– Receiving protection
• Not as much cooperation as exploitation
Commensalism
• One species benefits, the other is neither
helped nor harmed
• Clownfish & Sea Anemone
– Protection
– Feed on anemone’s leftovers