Download Ecosystems

ECOSYSTEMS
‘A World of Interactions’
Populations
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What is a
population?
When we talk about
populations what in
general do we mean?
A group of organisms of the same
species that live in a specific
geographical area and interbreed.
(Usually breed with members of their
own area.)
The group in general and the size of
the population, or the number of
individuals in it.
Community A number of interacting populations of species form a community
within an ecosystem within a specific geographical area . The total of the interactions can best be
represented as a food web.
Species Interactions
How Do Species Interact With Each Other?

There are 5 main types of species
interactions. They include: predation,
competition, parasitism, mutualism,
and commensalism.
Predation
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In predation, one organism eats and kills
the other organism. The organism that is
eaten is called the prey, and the one that
does the eating is called the predator.
Predators limit the population size of their
prey. Also, they tend to feed on old and
weak individuals who are more likely to
die anyway.
Predation…
This red-tailed hawk (predator) has captured
a snake (prey) for dinner. Yum!
Competition

Competition is a relationship between
species in which they attempt to use
the same resource. Species can
compete for: food, sunlight, territory,
pollinators, mates etc…
Competition…
Here, two reindeer compete for a mate.
Parasitism
Parasites are organisms that live in or on
another organism without killing it right
away.
 The organism the parasite takes its
nourishment from is known as the host.
The relationship between parasite and
host is called parasitism. Only one
organism benefits.

Parasitism…
http://www.youtube.com/wa
tch?v=rLtUk-W5Gpk
The deer tick (parasite) feeds off the blood of a
human (host), which can lead to the human getting
lyme disease
Mutualism

Mutualism is a cooperative partnership
between two species. Both species
benefit.
Mutualism…
The butterfly benefits from the flowers nectar, the
flower in turn benefits from having its pollen
dispersed.
Commensalism
Commensalism is a relationship in which
one species benefits and the other is
neither harmed nor helped.
 It is the rarest type of species interaction.

Commensalism…
Burdock uses its ‘velcro’ to attach to animals as they
pass, this helps to spread its seeds. The plant benefits
(seeds are Spread) while the animal is neither helped
or harmed.