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Species Interactions
5 Major Types of Species Interactions
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Symbioses are interactions between
species.
Predation
Parasitism
Competition
Mutualism
Commensalism
Predation
Species Interactions
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Predation
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One individual captures, kills, and consumes,
another individual (predator-prey).
Evolution (natural selection) favors adaptations
Helps to regulate populations size
Predation
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Predators survival depend on their ability to catch
prey.
The prey’s survival depends on its ability to avoid
being captured.
What types of adaptations could prey have
to avoid being captured?
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Possibilities
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Speed, mimicry, camouflage, bright colors to warn
of toxicity (poisonous)
Camouflage
Camouflage
Camouflage
Leaf Mimic Insect
Camfouflage
Brookesia superciliaris chameleon in leaf litter.
Mimicry
Poison arrow dart frog (below)
Mantella Frog (above) resembles
the poisonous poison arrow dart
frog.
Mimicry
Mimicry
The owl butterfly mimics the eye of a potential predator to scare off an
attacking individual.
Plant-herbivore interactions
Another Form of Defense
Animals that eat plants are considered to
be in predator - prey relationships.
 Some plants synthesize chemicals known
as secondary compounds that are
poisonous or irritating to the herbivore
consuming them.
 Example: Poison ivy
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Parasitism
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Parisitism is an interaction where one
organism benefits and the other organism
is harmed.
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How is this different than predation?
Vocabulary
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Parasite- The individual that benefits.
Host – The individual that is harmed.
Parasitism Vocab Cont…
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Parasites are divided into two categories
based on their interaction with the host.
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Ectoparasites – External parasites that do not
enter the hosts body.
Endoparasites – Parasites that are internal and
live inside the hosts body.
Ectoparasite or Endoparasite?
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Ascaris
Lives in the intestine.
May be fatal if the
larvae infiltrate vital
parts of the body.
Ascaris life cycle
Ball of Ascaris passed
from a host’s intestine.
Ectoparasite or Endoparasite?
Ectoparasite or Endoparasite?
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Fleas
Ectoparasite or Endoparasite?
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Ticks
Ectoparasite or Endoparasite?
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Leeches
Ectoparasite or Endoparasite?
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Hookworm
Found in approximately
25% of the world’s
population.
Larva enter through the
skin, find their way into
bloodstream and migrate
to the lungs and are
eventually swallowed,
living in the intestines up
to 10 years.
Cause abdominal pain and
iron deficiency.
Ectoparasite or Endoparasite?
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Pinworm –Extremely
contagious.
Affects 80% of children
between ages of 2 and 10.
Female lays eggs outside
the anus during the night
and returns to the colon.
Person scratches and then
may reingest the eggs or
pass them.
Female may lay 15000
eggs in one night.
Evolution of Parasites
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Parasitism has stimulated the evolution of
defenses in hosts.
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Examples: Skin, openings such as eyes, mouth,
and nose are defended with tears saliva and
mucus. Parasites passing through these
openings may be attacked by the immune
system.
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Adaptations of Parasites
Parasites adapt to efficiently exploit their host.
Why would a parasite want to efficiently use the
host?
Examples: The tapeworm are so specialized that
they have no digestive system. They live in the
small intestine and absorb nutrients through the
skin.
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Competition
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Competition results from the use of the same limited
resources by 2 or more species (niche overlap).
The more resources the 2 species share the more intense
the competition.
Competitive exclusion is when one species is eliminated as
a result of competing for the same limited resource.
Character displacement is when competitors evolve niche
differences or anatomical differences that lessen the intensity
of competition. The difference is often greatest where the
competitors overlap.
Competition
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Resource partitioning is when the similar
species coexist but each species only uses
part of the available resources.
Mutualism
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Mutualism is a cooperative relationship in
which both species derive some benefit.
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Some relationships are so close that the
individuals may not survive without the other.
One of the most important mutualistic
relationships is pollination.
How does pollination work?
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Animals that carry pollen are called pollinators.
 Examples birds, bees, butterflies, beetles, moths etc…
Pollination is one of the most important
mutualistic relationships on earth.
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Moth collecting nectar.
Many types of organisms are pollinators.
Termites are unable to digest wood so they
ingest a bacteria that digests it for them.
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Termites
Bacteria
Lichens
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Lichens are symbiotic associations of a
fungus with a photosynthetic partner
(photobiont) that can produce food for the
lichen from sunlight. The photobiont is
usually either green alga or
cyanobacterium.
remarkable 3-way mutualism appears to have evolved between an ant, a
butterfly caterpillar, and an acacia in the American southwest. The
caterpillars have nectar organs which the ants drink from, and the acacia
tolerates the feeding caterpillars. The ants appear to provide some protection
for both plant and caterpillar. Research of Diane Wagner, American Museum
of Natural History Southwestern Research Station
Egyptian Plover Bird
The Egyptian Plover Bird picks leeches out of the teeth of the crocodile.
How does this benefit the crocodile? How does this benefit the Plover
Bird
Commensalism
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Commensalism is a relationship in which
one individual benefits and the other is
unaffected.
Cape Buffalo and Cattle Egret
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Cape buffalo in Tanzania
The egrets feed off of
lizards and insects
forced out of hiding
while the buffalo
moves through the
grass.
Barnacles on a Whale
Question?
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Explain how predators differ from
parasites.
Question
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Some harmless flies resemble bees and
wasps. What is this mechanism called?
Why is it important?
Question
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If cattle egrets removed ticks from Cape
buffalos would their relationship still be
commensalism?
Question?
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Explain how two similar species of birds
are able to inhabit the same area and
even nest in the same tree without
occupying the same niche.
Question?
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What is the advantage of character
displacement?