Download Community and Symbiosis

Community Ecology
Species Interaction
Predation
In predation, an individual of one species,
called the predator, eats all or part of an
individual of another species, called the prey.
Many types of organisms can act as predators
or prey.
A predator’s survival depends on its ability
to capture food, but prey’s survival
depends on its ability to avoid being
captured.
Plants cannot run away from a predator, but many
plants have evolved adaptations that protect them
from being eaten.
Physical defenses such as sharp thorns, spines,
sticky hairs, and tough leaves can make plants more
difficult to eat.
Competition
Interspecific competition is a type of
interaction in which two or more
species use the same limited
resource. For Example, both lions
and hyenas compete for prey such as
zebras.
If two species compete for a resource, the result
may be a reduction in the number of either
species or the elimination of one of them.
More often, one species will be able to use a
resource more efficiently than the other. As a
result, less of the resource will be available
to the other species.
Symbiosis
A symbiosis is a close, long-term
relationship between two organisms.
Three examples include:
• parasitism
• mutualism
• and commensalism
Parasitism
• Parasitism is similar to predation in that
one organism, called the host, is harmed
and the other organism, called the
parasite, benefits.
• (Example – Human and tapeworm.)
Mutualism
Mutualism is a relationship in which two species
benefit from each other.
Some of these relationships are so close, that
neither species can survive without the other. (It
is sometimes called obligate mutualism Ex:termite and trichonympha)
• The Clown Fish and its Sea Anemone partner
both benefit from the relationship: The fish gets a
safe home that protects him from predators, and
he fiercely protects his sea anemone. He also
feeds the anemone. (It is also called
Protocooperation because each can survive
without the other.)
Pollination is one of the most
important mutualistic relationships
on Earth.
Commensalism
Commensalism is an interaction in which one
species benefits, and the other species is not
affected. (from english “sharing of food” or from
latin “sharing a table”)
Originally, the term was used to describe the use of
waste food by second animals (scavengers), like the
carcass eaters that follow hunting animals, but wait
until they have finished their meal.
Cattle egrets eat insects and lizards that
are forced out of hiding by the movement
of Cape buffaloes in Tanzania. (The birds
occasionally feed on ectoparasites on the
buffalo, but generally the buffalo do not benefit from
the egrets)