Download Species Interactions

Species Interactions
Symbiosis = close living relationship (some text use this to mean the same as mutualism
Relationship
Spp 1
Spp 2
Definition
Example
Mutualism
+
+
Both species benefit,
neither are harmed
Commensalism +
0
One or both species
benefit, but neither are
harmed
Saprophytism
+
0
Exploitation Parasitism
+
-
Exploitation Predation
Scavenging
+
-
+
-
Exploitation Herbivory
(Grazing)
Exploitation Herbivory
(Browsing)
Competition
+
-
One species feeds of
decaying matter from
another organism
One species lives in or on
and feeds off another
(host)
One species hunts and
feeds off another
One species feeds on leftover food from the kill of
predators
One species feeds on the
tissue of soft plants
Lichen is a combination of a
fungus (absorbs minerals and
water) and an alga
(photosynthesises).
Rhizobium (nitrogen-fixing
bacteria) in root nodules of
legumes (which provide
carbohydrates and space to
live).
The remora fish attaches itself
to a shark, hitches a ride, and
scavenges when the shark
makes a kill.
Fungi living on dead wood.
+
-
One species feeds on the
tissue of woody plants
Pandas eating bamboo
-
-
Both species are harmed
as they compete for
resources
Plants in a forest competing for
light.
Animals competing for space.
Amensalism
0
-
One organism is inhibited,
the other is unaffected
Shade from trees allow only
light tolerant plants to grow.
Antibiosis
0/+
-
One species is unaffected
(or benefits), the other is
Rhubarb producing oxalic acid,
which prevents other organisms
Fleas living on a dog.
Tapeworms living in a mammal’s
gut.
Spiders feeding on insects.
Hyenas eating a zebra after lions
have killed it
Cows and sheep eating grass
harmed by a poison/toxin from growing.
from the first
Penicillium mould (blue-green,
powdery) producing penicillin,
which inhibits the growth of
bacteria.
Clearing confusion on Amensalism vs Antibiosis vs Allelopathy
Amensalism is a site-specific relationship in which one population is inhibited while the other is unaffected.
A simple example is the shading out of certain plants under tall trees. The trees reduce the available
sunshine at ground level, and numerous plants cannot find adequate light in the shade. Hence, only shade
tolerant plants with lower light requirements can survive as ground cover in the forests.
Antibiosis is a specific type of amensalism in which one organism produces a metabolite that is toxic to other
organisms. The best known example is mold, penicillin, which produces an antibiotic substance causing the
death of many bacteria. Many plants also produce substances which are harmful to animals, for example,
algae blooms of some blue, green and red algae produce chemicals that are toxic to fish.
Allelopathy is an example of antibiosis where a PLANT produces a chemical that inhibits or is toxic to other
plants, soil organisms or herbivores. Eg walnut leaves have a chemical that inhibit other plants. Gum tree
roots do this too!
SOME TEXTS consider the effects of both antibiosis and allelopathy to be + / 0 (0 to the inhibited organism).
Definitions for allelopathy vary. Some use only for chemicals released by plants.