Transcript Community Ecology and Symbiosis

Community Ecology
Species Interaction
“Just as populations contain interacting
members of a single species,
communities contain interacting
populations of many species.” – Holt Modern Biology
– Ch 20
Probably the most interesting predatory aspects is
that of the Lizardfish / Goby interaction. The
lizardfish that prey on gobies are not much larger
than the food they eat. In fact, a 5 cm lizardfish
can eat a 3 cm Hawaiian Shrimp Goby!
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.
• The predator species (in the illustration below, the Lion
(Panthera leo) kills and consumes the prey species (in
this case, a Cape Buffalo (Syncerus caffer).
Linx chasing Hare
• Lady bug (“ladybird beetle”) preying on an
aphid.
sundew carnivorous plant
•
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.
Both lose!
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.
Competition – Anole lizards
• The Green Anole (Anolis carolinensis)
is native to the southern United States.
In the 1960's, The Brown Anole
(Anolis sagrei) was introduced from Cuba.
• The two species vie for habitat and food resources, and
it appears that the exotic Brown Anole has displaced the
native Green Anole in some physical spaces, such as
lower shrubbery and grass.
• The Green Anole generally lives higher up in the trees
and foliage than the Brown Anole does. This result of
competition is known as resource partitioning.
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
ascarus
tapeworm
The Human Head Louse
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.)
Nemo lives in
an anemone.
Pollination is one of the most
important mutualistic relationships
on Earth.
Ants & Acatia Trees in Central America.
The ants live in the thorns and gain food from the
acacia. The ants defend the acatia from insect
herbivores.
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)