Transcript Types of Species Interactions

Types of Species
Interactions
Species interactions
• In every ecosystem species interact in a variety of ways.
– They can be positive (+) , negative (-) , or have no effect (0).
• Each species develops adaptations to deal with these
interactions.
• If a species cannot adjust to it’s community members (two
species in the same niche) then it will go locally extinct.
Symbiosis
• Close interaction
between species.
• 5 types of
symbiosis
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–
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–
Predation
Parasitism
Competition
Mutualism
Commensalism
Think: Which community is most diverse
and why.
Predation
• Predators
capture, kill, and
consume prey.
– Predators are
adapted to role.
– Prey are adapted
to survive
predator
• (+,-)
Think: Which species determines the number of the
other. (or is that a trick question??)
What adaptations do each of these organisms have in
their role as predator or prey?
Parasitism
• Parasite is helped.
• Host is harmed.
– Ectoparsites
body, e.g. Tick)
(outside of
– Endoparasites (inside
body, e.g. Tape worm)
• (+,-)
think: Why does a parasite usually not
kill its host?
Some caterpillars like this one have growths that look like
parasite eggs to discourage a parasitic wasp from laying
eggs on them. (I’ve seen them in tropical forests)
Mutualism
• Both species benefit.
• Lichens
–
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–
2 layers of fungi
Algae cells inside.
Algae is kept moist
Fungi get food.
• (+,+)
Do you think that mutualism
relationships species specific? Why?
Commensalism
• One species benefits.
• One species is not effected.
– Lichens growing on a tree
limb.
– Cattle egrets and live stock.
• (+,0)
The whale is
not harmed by
the barnacles,
but the
barnacles
benefit by
getting food & a
place to live.
Competition
• Results from niche
overlap.
– Competitive exclusion.
– When two species
directly compete, one
will go extinct.
Think: What, most likely, is being
competed for in this study?
Strategies to avoid Competition
– Character displacement
• Competitors evolve to
different niches.
– Resource partitioning.
• Each competing species
uses a portion of the
resource.
– Results in less
competition between
species.
Think: How do the Barn Owl and Red Tail
Hawk demonstrate character displacement.
Communication: Signals in
color
• Mimicry
– Prey evolve
defenses
through natural
selection.
– Coloration
mimics poisonous
organism.
– Warning
coloration
Plant defenses
• Plants are defending
against herbivory.
– Thorns, spines, sticky
hairs.
– Secondary chemicals
•
•
•
•
Nicotine
Strychnine
Digitalis
Poison oak
Summary Review
1.
Explain symbiosis and give an
example of each kind.
2. What is the difference between
Ectoparsites and Endoparasites?
3. Name two ways plants defend
against herbivory.
4. In what ways to similar species
avoid competition?
(paragraph form)