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Ecology
Topic 6 and 7
Topic 6 ecology
Organisms and their environment:
An organisms environment is
everything living and nonliving that
surrounds an organism.
Describe your environment:
Parts of an ecosystem:
an ecosystem is made up of all living
things that interact with one another.
Interacting living things are termed
biotic factors
When scientist study ecosystem they
also study non-living things such as soil.
Non-living parts of an ecosystem are
termed abiotic factors
Abiotic factors include things like
rainfall, acidity, temperature,and
amount of light.
Environmental limits on population size
Living things could produce
populations of infinite size if
resources were infinite.
Limiting factors in an ecosystem:
oxygen
water amount, pH and temperature
carbon dioxide
nutrients
space
Sunlight and temperature
All of these are finite resources.
That means that they will run
out.
This creates competition among
organisms for the resources.
The populations will overpopulate
an area and then die off,
creating a stable population.
Biotic factors located in different
environments, containing different
abiotic factors
The number of
organisms of a single
species that an
ecosystem can support
is referred to as it
carrying capacity.
This is determined by
both the biotic and
abiotic factors in the
ecosystem
Hw Questions 1-9
Population interactions
•
Most interactions happen as
organisms obtain food.
• Every population is linked
directly or indirectly
• Each population has one or more
specific roles in the ecosystem
Roles in the Ecosystem:
• The role that each species plays in
an ecosystem is called its ecological
niche.
• Only one species at a time can
occupy a particular niche. More than
one ends up with competition among
the species.
Competition for a particular ecological
niche happen when foreign species
enter an area.
• Zebra muscles– brought to great
lakes. Eat all the natural food and
overpower natural species.
• Purple loosestife takes
habitat of the native cattail
• Eurasian milfoil
TAKES UP SPACE AND NUTRIENTS FOR
NATURAL WATER PLANTS
•Non-native ladybug species.
NO NATURAL PREDATORS
Emerald ash borer
DESTRUCTION OF BLACK ASH TREES
Relationships in an ecosystem:
In every ecosystem ,populations are
linked together in complex webs of
interactions
Some relationships are competitive
fight for same resources
Some relationships are co-operative
whale and feeder fish
Some relationships are predator-prey
Some relationships are parasitic
Food Chains
Illustrate the
relationships
between
predators and
prey
The arrows
indicate the
direction the
energy flows.
All energy originally comes from the sun.
Autotrophs or producers turn the sun
energy into food
Heterotrophs or consumers get their
energy by consuming other organisms.
Three types of heterotrophs
herbivores-eat only plants
Carnivores – eat only meat
Omnivores- eat both plants and animals
Decomposers recycle materials
that can then be used by
producers.
Other types of relationships that
exist: Scavengers and
Parasite/Host
Food webs:
these show the
inter connected
food chains
Hw:
Questions 10-27
Energy Flow Through an Ecosystem
Solar energy is the primary energy source for
most living things in our biosphere. This solar
energy is first captured by producers.
Primary consumers get their energy from the
producers they eat.
Secondary consumers get their energy from
their prey, etc, etc.
A lot of that energy is lost as heat from the
organisms
This means that each link in a food chain has less
energy available to use for itself.
If we use a box to represent the energy available
in each link of the food chain and stack them
starting with the producers at the bottom, we
create an energy pyramid.
Food Chain
Energy Pyramid
Eagle
Tertiary Consumers
Snake
Secondary
Consumers
Cricket
Primary
Consumers
Grass
Producers
Recycling and Reusing
Every last bit of the energy stored in an
organism’s body gets used.
Decomposers get whatever energy that’s
left in a dead organism,
but they also make sure that the raw
materials that made up the organism’s
body are returned to the soil so that
producers can start the process all over
again.
It may seem kind of gross to you, but think
about all the organisms that survive by
breaking down dead organisms.
These are the decomposers (some
bacteria, fungi, worms, etc) and they fill a
vital role in any ecosystem.
Without raw materials being returned to
the soil, producers can’t survive.
What would happen to the energy pyramid
if the bottom level got too small? (Think
“Jenga”)
Vital Raw Materials
As “raw materials” are taken from the
environment, used, and returned, material
cycles are created.
Some of the most important material
cycles are listed below:
Water
Carbon
Nitrogen
Phosphorous
The decomposers play important roles in
most of these cycles.
Without them, the ecosystem would
eventually collapse.
Homework: (#28-39)
Diversity in an Ecosystem
Our biosphere, Earth, is made up of
many different ecosystems. Each with
it’s own special characteristics.
Organisms with adaptations that
allow it to survive in an ecosystem
play a special role in that ecosystem.
They fill a niche.
If a niche is left unfilled, the ecosystem would
be thrown out of balance, affecting every
organism living in it.
The resulting variety of organisms that
evolved in each niche is called biodiversity.
The greater the biodiversity of an
ecosystem, the more stable the
ecosystem is.
If something catastrophic happened to
one species, another may be able to fill
it’s niche and balance the ecosystem
again.
Factors Affecting Biodiversity
Biodiversity can be lost due to a number of
factors, some natural, and some man-made.
Habitat destruction, for whatever reason, can alter
an ecosystem forever. Although some organisms
may be able to eventually return to an area
devastated by a disaster, organisms that filled
critical niches might never return.
If the interdependence of the organisms in the
ecosystem is too great, this loss of biodiversity
can ensure that the ecosystem never returns to
it’s original state.
The Human Factor
Besides human-caused habitat destruction, humans also contribute to
the loss of species in several other ways, direct and indirect.
Examples:
Removal/killing of predatory species.
1) Removal of natural predators allows prey
species populations to explode.
2) Overpopulation of the prey species results
in drastic reductions of their food supply
through overgrazing. Mass starvation
occurs.
3) Overgrazing destabilizes the soil, allowing
erosion of soil…even fewer
plants…more starvation…fewer
species…
Another Example:
Agriculture
1) Farmers grow hundreds of acres of one type of
crop.
2) The crop is in constant danger from disease
and pests.
3) This man-made loss of biodiversity sets the
stage for severe environmental
disruption.
In nature, biodiversity ensures that no single food
source is concentrated in that way. This makes it
more difficult for any single type of pest or disease to disrupt the
ecosystem.
Biodiversity is also extremely important as a resource.
Genetic material in various organisms is useful in making new
medicines, insecticides, etc.
Homework: Pages 111-112 (#40-45)
Environmental Changes
Ecological succession
In any ecosystem, all organisms living
within it interact with biotic and abiotic factors.
In this way, communities change their
environment.
As the environment changes, some
communities may have trouble adapting while
others may thrive. The communities may also
change as a result.
This change of habitat from one type to another is
called
ecological succession.
Example:
Grass grows in simple soil, but
creates deeper, richer soil when it
decomposes.
The deeper, richer soil can support
larger plants like shrubs and bushes. Grasses
decline.
Shrubs and bushes make soil
suitable for trees.
Trees replace them.
Acted upon by
Produces
Bare
Rock
Lichen
Pebbles
Pioneer Organism
Pebbles
Soil
Better
Soil
Fertile
Soil
Moss
Simple
Soil
Grasses
Better
Soil
Bushes
Trees
Climax Community
Fertile
Soil
Forest
Can a pond or lake ever become a forest?
The simple answer is “YES”.
HOW?
Homework: Pages 114-115 (#46-59)