Transcript Ecological Interactions

RELATIONSHIPS
Between Organisms:
Ecological Interactions: Symbiosis
What are some ecological groups?
▪ Population – group of individuals of the same species
▪ living in the same area, potentially interacting
▪ Community – group of populations of different species
▪ living in the same area, potentially interacting
What is symbiosis?
Literal definition: the act of living together
▪ What it means:
• Two organisms that live together
• Temporarily or for a longer time
• At least one of the organisms
benefits from the relationship
Why are ecological interactions important?
▪ Interactions can affect distribution and
abundance (amount).
▪ Interactions can influence evolution.
How the following interactions can affect
distribution, abundance, and evolution?
Types of ecological interactions:
All relationships can benefit, harm or not affect the
chance of another organisms survival.
1) Mutualism – two species provide resources or services to
each other
 enhances fitness of both species
Mutualism Example A
Antelope
gets rid of
parasites
Oxbird gets
a meal
Mutualism Example B:
▪Moray Eel gets
a clean mouth
Cleaner Fish
gets a meal
Here are three other examples of mutualistic relationships:
C. The bee and the flower. This benefits
the plants. In this relationship, the bees get
to eat, and the flowering plants get to
reproduce.
D. The spider crab and the algae. The
algae gets a good place to live, and the
crab gets camouflage.
E. The bacteria and the human. The
bacteria benefit by getting food, and the
human benefits by being able to digest the
food it eats.
2) Commensalism – one species receives a
benefit from another species
 enhances fitness of one species; no effect on
fitness of the other species
Commensalism Examples:
A) Cattle and Egrets: Cattle stir up
insects as they eat grass.
Egrets hang around and eat
insects
B) Remora Sharks: They “Hitch” a
ride on larger animals and
gather food along the way.
Other examples of commensalistic
relationships:
C. Barnacles adhering to the
skin of a whale : The barnacle
benefits by filtering food as the
whale swims. Its does not seem
to affect the whale.
D. Sea Anemone and Clownfish:
Clown fish gets protection
Anemone is unaffected
http://www.youtube.com/watch?v=eWXOurnVTYg
E. Birds and Trees:
Birds build nests in
trees.
3) Predation – one species feeds on another
 Enhances fitness of predator but reduces fitness
of prey
herbivory is a form of
predation
Predation Examples:
A) Cattle and grass: Cows eat
and kill the grass for food.
B) Wolf and Deer: Wolf kills
and eats deer for food
C) Baleen Whale and
plankton: Whale filters
plankton from water as it
swims.
D) Lynx and
Snowshoe
Hare:
As you can see
by the graph,
their
populations are
directly linked.
4) Parasitism – one species feeds on another
 Enhances fitness of parasite but reduces fitness
of host. It is in the parasite’s best interest not to
kill the host.
Parasitism Examples:
A) Ants and Acacia Tree: lay eggs on
acacia tree, Acacia covers the infected
area with brown flesh (gall)
B) Tapeworm and Cow: They get food by
eating the host's partly digested food,
depriving the host of nutrients.
C) Fleas and Cats: fleas bite the Cats skin,
sucking their blood, and causing them to
itch and possible get sick. The fleas, in
turn, get food and a warm home.
D) Wasp eggs on back of
caterpillar.
Parasitism
E) Sea lampreys feed on
fluids of other fish.
F) Mosquito biting a
human.
5) Competition – two species share a limited
resource
 reduces fitness of one or both species
Here are three examples of
competition relationships:
A. Spruce and Pine Tree: They
must compete for light, water
and nutrients.
B. Cheetahs and Lions. They
must compete for the same prey
such as zebras.
C. Coyotes and bobcats: They
compete for the same prey such
as rabbits.
competition relationships
continued:
D. Hyenas and Lions in Africa:
fight over gazelle
E. Rams: compete with each
other for mates.
F. Gray Squirrels and Red Squirrels: Until Americans introduced gray
squirrels into parts of England in the early 20th century, red squirrels
had been the only species of squirrel in the country. The gray squirrels
were larger and bred faster and successfully competed for resources.
Within a couple years of overlap in an area, the red squirrels
disappeared.
6) Amensalism is a relationship in which a product of
one organism has a negative effect on another
organism.
▪ A) Penicillium and bacteria: penicillium
secretes penicillin, a chemical that kills
bacteria.
▪ B) Black Walnut Tree and other plants:
The Black Walnut gives off a chemical that
harms or kills some species of neighboring
plants.
▪ C) Sheep and grass: Sheep make trails by
trampling on thereby destroying a food
source.
7) Neutralism: describes the relationship
between two species which interact but do not
affect each other.
▪ Neutralism describes interactions where the fitness of one species
has absolutely no effect whatsoever on that of the other.
▪ True neutralism is extremely unlikely or even impossible to prove.
▪ When dealing with the complex networks of interactions presented
by ecosystems, one cannot assert positively that there is absolutely
no competition between or benefit to either species.
▪ Since true neutralism is rare or nonexistent, its usage is often
extended to situations where interactions are merely insignificant or
negligible.