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Ecology
Species
• Group of similar organisms that can breed and
produce offspring.
Population
A population is all the members of a given
species in a given area.
Example - All the turtles in a lake.
Habitat
The physical location
where plants and
animals live is called a
habitat. A habitat is
filled with different
species, each of
which depends on the
habitat’s resources to
meet its needs.
Niche
Each of the
organisms that
lives in a habitat
has a role to play in
its habitat, a role
which is referred to
as its niche.
Community
Community – All the species that live and
interact in a given area constitute a
community.
Ecosystem
All the living things along with their
environment form the Ecosystem.
Biome
Regions of Earth that are similar in climate and have similar
types of plants are called biomes.
Biosphere
The part of the earth where life exists
including land, water, air, and atmosphere
Levels of the environment:
•Biome
•Ecosystem
•Community
•Population
•Organism
Organism
A single
individual
animal, plant,
fungus, or
other living
thing.
Population
A group of
organisms
of the same
species that
live in the
same area.
Community
All the living
components of the
ecosystem form a
community. Different
plants, animals, and
other organisms
interact with each
other.
Ecosystem
An ecosystem
consists of the
living things
and their
environment.
Biome
The climate
and types
of plants
that are
found in
similar
places
around the
world.
Levels of Organization
• Ecologist study
organisms ranging
from the various
levels of
organization:
– Species
– Population
– Community
– Ecosystem
– Biome
– Biosphere
Interactions Among Organisms Organisms interact in different ways:
• Predator and Prey
• Competition
• Cooperation
• Symbiosis Mutualism
Commensalism
Parasitism
Predator and Prey:
The predator
is an animal
that eats
another. The
prey is an
animal that
is eaten by a
predator.
Competition:
Competition is
the struggle
between
individuals or
different
populations for
a limited
resource.
Cooperation
Cooperation
is an
interaction
in which
organisms
work in a
way that
benefits
them all.
Symbiosis
The relationship between individuals of two
different species who live together in a close
relationship is called symbiosis.
A symbiotic relationship may affect the partners
in different ways :
• Mutualism - Both species benefit from the
relationship.
• Commensalism - One species benefits while the
other is not affected.
• Parasitism - One species benefits while the other
is harmed.
Mutualism
Mutualism is an
interaction between
two species that
benefits both.
Example -The
relationship between
a flower and a bee.
The bees get food in
the form of nectar,
and the flowers get
pollen from other
flowers, which they
need to make seeds.
Mutualism -
Mutualism
The oxpecker gets food (ticks and insects) and a safe haven from the rhinoceros,
and the rhinoceros has parasites (ticks) removed.
Commensalism
Commensalis
m is a
relationship
between two
species in
which one
species
benefits while
the other is
not affected.
Parasitism
Parasitism is a
relationship
between two
species in which
one species
benefits while
the species it
depends on, its
host, is harmed.
The End
Ecosystems are always changing Populations change over time because of
Growth or Decline –
•
•
•
•
Birth Rate
Predator-Prey Interactions
Lack of Nutrients/Abiotic Factors
Pollution
Limiting Factors Limiting Factors - Any factor or condition
that limits the growth of a population in
an ecosystem is called a limiting factor.
These could be biotic factors or abiotic
factors.
Limiting Factors
Carrying Capacity When a population reaches a state where
it can no longer grow, the population has
reached it’s carrying capacity, or the
maximum number of individuals that an
ecosystem can support.
An ecosystem’s carrying capacity is
different for each population.
Succession Succession is the gradual change in an
ecosystem in which one biological
community is replaced by another. Over
time the grasses of open farmland are
slowly replaced by small plants and
shrubs, then trees. This change from field
to forest is an example of succession.
Succession
Primary Succession Very few places on Earth are without
some form of life. Even when a lava flow
covers an area or a glacier retreats and
leaves behind an empty and barren
environment, plants will move into the
area and bring it back to life. These are
examples of primary succession, the
establishment of a new biological
community.
Primary Succession at Glacier Bay, Alaska
A climax community is the stable
community at the final stage of
succession.
Primary Succession
Pioneer Species The first plants that move into an empty and
barren area and bring it back to life are called
Pioneer Species.
As the pioneers grow, they gradually weaken the
rock surface. The rock breaks down and
weathers over time. Decaying plant matter adds
nutrients, forming soil. A variety of small plants
and shrubs take root. These plants, in turn,
support insects, birds, and small rodents.
Eventually there is enough soil to support
coniferous trees. Forests grow, providing a
stable habitat for larger animals.
Secondary Succession Secondary succession takes place after a major
disturbance to the biological community in a
stable ecosystem. A community can be disturbed
by a natural event, like fire or flood, or by
human activity. Despite the disturbance, the soil
remains there. The damage, is surface damage
only. Below the surface, seeds and plant roots
survive. Gradually grasses and small shrubs
grow up among the decaying remains of the
original plants. Birds, insects, and rodents
return. Alder trees take root and put nutrients
into the soil. Over time, a variety of trees and
plants grow, providing food for numerous
animals.
Secondary Succession
Ecological Succession
Ecological succession is the set of
changes in community
composition that occur over time
in a new or disturbed community.
Succession after
the Yellowstone
fires.
Succession at Mt. St.
Helens.
The final stable plant community may reach a point
of stability that can last for hundreds or thousands
of years.
The End