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5.1 Habitats and Niches
1. Describe the concept of the niche.
2. Examine how interactions between a
species and its environment define the
species’ niche
3. Infer how removal of an organism at
one trophic level can affect another
organism in the ecosystem.
5.1 Habitats and Niches
• Ecosystems can be large places. The
environment in one part of an ecosystem is
different from the environment in another part.
For example, the conditions near a stream may
be very different from those on a dry hill above
the stream.
• The organisms living in each part of this
ecosystem differ from each other.
Niches
• Every organism is adapted to live in its habitat.
For example, each organism has special ways of
gathering food, reproducing, and avoiding
predators. The actions of an organism define its
role in the ecosystem.
• The role of an organism in the ecosystem in
called its niche. A niche is more than an
organism’s habitat; it is also what the organism
does within its habitat.
Niches
• A niche includes both biotic and abiotic factors. Some
biotic factors that help define a niche are food sources
and predators. Abiotic factors include temperature,
amount of sunlight and water.
• All members of a species are adapted to the same
niche. No two species can share the same niche in the
same habitat or they will compete for resources.
• The extinction of a population due to direct
competition with another species for a resource is
called competitive exclusions.
Niche Diversity
• Niche diversity, the number of different niches
in an ecosystem, is often determined by abiotic
factors in the environment. In a marsh, for
example, there are many organisms. However,
there are few different niches because the
physical environment in a marsh is fairly
constant. By contrast, in a desert ecosystem,
there are few organisms but many different
niches.
Niche Diversity
• A predator is an organism that actively hunts
other organisms. The organism that is hunted is
the prey.
• Predators play an important role in increasing
niche diversity by decreasing the population size
of their prey species.
Predators
Predators help maintain diversity in ecosystems in
many ways. The Great Barrier Reef is one example. A
species of sea star called the crown of thorns lives and
feeds on the corals that make up the reef. In the past,
the crown of thorns was rare because it was eaten by
many species of predatory fish, but fishing by people
has removed many of the sea star’s predators. The
crown of thorns’ numbers increased, and they now
consume large stretches of the reef every year. The
destruction of the reef results in lost habitat to many
species, therefore lover diversity in the ecosystem.
The Great Barrier Reef
The Great Barrier Reef
The Great Barrier Reef
The Great Barrier Reef
• Brain Coral
The Great Barrier Reef
The Great Barrier Reef
The Great Barrier Reef
• Fire Coral
The Great Barrier Reef
The Great Barrier Reef
The Great Barrier Reef
The Great Barrier Reef
Lesson 6 - Homework
1. How is a niche different from a habitat?
2. What might happen to an ecosystem if all the
carnivores were removed? Explain your
answer.
3. Explain how the niche of one species might
influence the niche of another species.
4. List two examples of biotic factors and abiotic
factors that can limit or increase the size of a
species’ population.