Species Interactions
Brainstorm!
Species Interactions
What is “Fitness”?
Fitness: the ability of an organism to survive,
reproduce, and pass along genes to the next
generation
Species Interactions
Change in Fitness as a
Result of the
Interaction
+ net gain of fitness
0 no net change of
fitness
- net loss of fitness
Fitness: the ability of an organism to survive,
reproduce, and pass along genes to the next
generation
Predation
 Definition: One species eats
another
 Example: Carnivore,
omnivore, herbivore,
parasite, parasitoid
 Symbol: +/-
4
Parasitism
 one organism (parasite)
obtains its food at the expense
of another organism (host)
 Mosquitoes, tapeworms,
leeches
5
Prey Adaptations
6
Predator Adaptations
 Adaptations that predators
have that allows them to catch
their prey.
 Speed
 Agility
 Camouflage
 Packs
 Claws
 Teeth
Competition
 Definition: Neither organism
benefits from the interaction
(competition for the same
resources is often involved)
 Example: Different predators
competing for the same prey,
Oh Deer!
 Symbol: -/-
8
What can happen?
Competitive Exclusion
(There’s a winner and a
loser) 
9

ResourcePartitioning
(Divide up who gets to
use what resources)
Mutualism
 Definition: Both organisms benefit
from the interaction
 Example: cleaner wrasse cleaning
fish teeth, bees pollinating flowers,
digestive bacteria and humans
 Symbol: +/+
10
To The Aquarium!
 3 minutes per area—
making observations on the
Graphic Organizer
 Look for details (they will
make you happy!)
 Enjoy yourself, but
remember that you are a
scientist and an academic!
 Today, you may observe
the rays in the touch tank,
but save the touching for
another time.
11
Fitness?!?
Turn to your neighbor and remind each other what
“fitness” means in ecology
Fitness: the ability of an organism to survive, reproduce, and pass
along genes to the next generation
12
Neutralism
 Definition: Two organisms
interact but have no effect on
each other.
 Example: Some members of
tide pool communities
 Symbol: 0/0
* It is important to remember
that this is not the absence of
interaction. It is just that the
interactions do not impact the
fitness of either organism.*
13
Commensalism
 Definition: Interaction where one
organism benefits and the other
organism is neither harmed nor
benefitted.
 Example: Cattle egret and cattle,
barnacle and whale
 Symbol: +/0
14
Amensalism
 Definition: One organism
negatively impacts another
organism, but it not
impacted itself.
 Example: Penicillium
bacteria and other bacteria,
black walnut tree and other
plants (growth inhibitors)
 Symbol: -/0
15