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ECOLOGY REVIEW
Dr. Edelberg
What is ecology?
• Ecology is the study of interactions between
living things and between living and non living
things
What are abiotic factors?
• Abiotic factors include all the non living things
that living things interact with
• For example the sun provides energy, carbon
dioxide and water are needed for
photosynthesis. Oxygen is required for cell
respiration.
• Sun, water, carbon dioxide, oxygen are all
abiotic factors.
What are biotic factors?
• Biotic factors include all the living things and
once living things.
What are the levels of Ecological
organization?
• Populations-A group of organisms of the same
species that can mate, produce fertile
offspring, and live in same location.
• Community-A group of interacting populations
living in the same area (includes only biotic
factors).
• Ecosystems-Community (all the living) plus all
abiotic factors in a particular location.
Energy flow in an ecosystem
• All organisms require energy
• Solar energy provides practically all the energy
for ecosystems.
• Living things in an ecosystem can be classified
according to how they obtain energyautotrophs or heterotrophs.
• Autotrophs convert energy from the sun into
chemical energy stored in the bonds of
organic molecules (photosynthesis).
Energy Flow continued
• Heterotrophs can’t produce their own food directly
from sunlight and inorganic compounds. They require
energy previously stored in organic molecules.
• Autotrophs are called primary producers
• Heterotrophs can be grouped as consumers or
decomposers
• Consumers can be herbivores, carnivores, omnivores or
detritvores-invertebrates that feed on organic wastes
and dead organisms.
• Energy flow is one directional moving from sun to
producers to consumers to decomposers and
eventually lost as heat (can’t be reused).
What is a food chain?
• A food chain is a simple model that shows
how energy and nutrients move through an
ecosystem.
• A food chain is composed of feeding levels
called trophic levels
What are the trophic levels?
• First trophic level are the primary producersmake their own food
• Second trophic level are the primary consumersobtain food by eating producers. They are
considered herbivores because they eat only
plants.
• Third trophic level- are the secondary consumersobtain food by eating primary consumers. They
are considered carnivores if they eat meat or
omnivores if they eat meat and plants.
What are the trophic levels-continued
• Fourth trophic level-are the tertiary
consumers-obtain their food by eating
secondary consumers.
• Decomposers are considered a trophic level
but have no number because they feed on
other trophic levels. Break down dead
material into inorganic material. Bacteria and
fungi are the main decomposers.
Energy flow in an ecosystem
Food
chains
What is the amount of energy
available at each trophic level?
• 90% of energy lost in each trophic level
• Producers (1st trophic level) get 100% of
energy available.
• Primary consumers (2nd trophic level) get 10%
of available energy.
• Secondary consumers (3rd trophic level) get
1% of available energy.
• Tertiary consumers (4th trophic level) get 0.1%
of energy available.
Energy available continued
• Thus the amount of energy available limits the
food chain to 4-5 links.
• The greatest amount of energy is in the first
trophic level and the least amount of energy is
in the higher trophic levels
• More efficient to feed at lower trophic levels
Ecological pyramids
• Ecological pyramids are models that show
amounts at each trophic level and the change
from level to level.
• Energy pyramids show the amount of energy at
each trophic level.
• Biomass pyramids show the amount of biomass
(dry weight of living tissue) at each trophic level
• Numbers pyramid shows the number of
organisms at each trophic level.
Energy pyramid
• Shows that each higher trophic level must
have less energy than lower levels due to loss
of energy as heat (via cell respiration) at each
level.
Numbers pyramid
• Numbers pyramid indicates the number of
individuals in each trophic level.
• Sometimes get inverted numbers pyramid.
For example one tree can support many
consumers.
• Energy pyramids can never be inverted.
Biomass pyramid
• Pyramid of biomass shows amount of biomass
at each trophic level. Can’t be inverted.
What is a food web?
• A group of interconnecting food chains.
• Shows all the possible feeding relationships in
an ecosystem.
• More realistic than a food chain since most
organisms feed on more than one thing.
FOOD WEB
Nutrients also move through
ecosystems
• Nutrients move through ecosystems vias
trophic levels
• Unlike energy, nutrients are recycled
• Nutrient cycles include the water cycle, carbon
cycle, nitrogen cycle, and phosporus cycle
Water Cycle
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Evaporation
Transpiration-Leaf sweating
Condensation
Precipitation
Runoff
Carbon Cycle
• Atmospheric carbon dioxide (burning fossil
fuels and cell respiration)
• Death and decay result in fossil fuel formation
• Photosynthesis (remove carbon dioxide from
air and move carbon to glucose housed in
living things).
Carbon Cycle
Nitrogen cycle
• Bacteria capture nitrogen and bring it into
living things
• Different bacteria return nitrogen back to
atmosphere.
Community ecology focuses on
interactions between organisms
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Types of interactions include
Competition
Predator-prey
Symbiotic
Competition
• Increases between specie swhen resources are
scarce
• Niche is the role in plays in an ecosystem (how
does it meet its food need?, Shelter? How and
where it survives? how and when it
reproduces?)
• Habitat is location that it lives. Habitat is one
small part of an organisms niche.
Competitive exclusion principle
• States that no two species can occupy the
same niche at the same time.
• Possible outcomes include extinction of one
species or resource partitioning-splitting up of
niche
Predator-Prey Relationships
• A predator eats prey
• Since no community can carry more organisms
than its food, water, and shelter can
accommodate it must stay in balance.
• Ecosystems will fail if they do not stay in balance.
• To stay in balance predators and prey develop
adaptations-any inherited behavior or structure
that provides a survival advantage in a particular
environment.
Predator-prey continued
• Predator adaptations include teeth, claws, fangs,
poison, heat sensing organs, speed and agility
• Outcomes of predator-prey interactions include
offset oscillations in the population sizes of the
predator and prey-as the predator population
increases the prey population decreases, as the
prey population decreases the predator
population decreases, as the predator population
the prey population increases causing the
predator population to increase.
Predator-prey continued
• Another outcome may be co-evolution of
predator prey. Each acts as a selective
pressure on the other for adaptations. Each
adapts to changes in the other.
Symbiosis (living together)
• A close and permanent relationship between
two organisms of different species
• Three types of symbiotic relationshipsmutualism, commensalism, and parasitism
Mutualism
MUTUALISM-a
symbiotic relationship
where both species
benefit symbiotic symbiotic
• AAAAA
relationship where both species
benefit e.g.
1.
2.
3.
4.
Clown fish and sea anemone
Humans and pets
Ants & Peony flowers
Lichens – algae and a fungus
Commensalism
• A symbiotic relationship in which one species
benefits and the other is neither helped nor
harmed.
Parasitism
• A symbiotic relationship where one organism
benefits and the other is harmed.
Succession
Both the biotic or living and the abiotic or nonliving components of an ecosystem change over
time.
• Will this landscape of rocks remain this way
forever?
The answer is, “NO!”
• Over the years, one kind of community is
replaced by another kind of community until
eventually, a stable community develops.
• The gradual change in a community is known
as succession.
Two Types of Succession
• Primary Succession: The process of creating
life in an area where no life or soil previously
existed.
• Secondary Succession: The process of rerebuilding a previously existing community
after being destroyed by some disaster like
fire. Soil exists.
Primary succession
• The development of an ecosystem in an area
that has never had a community living within
it occurs by a process called PRIMARY
SUCCESSION.
• An example of an area in which a community
has never lived before, would be a new lava
or rock from a volcano that makes a new
island.
Primary Succession
• Begins in a place without any soil
– Sides of volcanoes
– Receding Glaciers
• Starts with the arrival of living things such as
lichens that do not need soil to survive.
• Called PIONEER SPECIES
• Lichen is a classic Pioneer species
Pioneer Organisms
• Primary succession on land begins in an area where
there are no living things and no soil.
• The first plants or plant-like organisms that arrive are
called pioneer organisms.
• They can grow on bare rock without soil eventually
breaking it up and helping soil to form. These include
lichens and algae.
Modification of the environment
• Soil starts to form as lichens and the forces of weather and
erosion help break down rocks into smaller pieces.
• When lichens die, they decompose, adding small amounts of
organic matter to the rock to make soil
Creation of New Soil
• Creation of soil allows plants to grow.
Primary Succession
• Simple plants like mosses and ferns can grow
in the new soil
Primary Succession
• The simple plants die, adding more organic
material.
• The soil layer thickens, and grasses,
wildflowers, and other plants begin to take
over.
• Then These plants die, and they add more
nutrients to the soil.
• Shrubs and tress can now survive now.
Primary Succession
• Insects, small birds, and mammals have begun
to move in.
• What was once bare rock now supports a
variety of life.
Pictures of Succession
• One sequence of plant succession in New
Jersey might be lichens----then----grasses--shrubs----conifers (pine trees)----deciduous
forests(beech and maple trees).
Climax Community
• Succession ends with the development of a
climax community. Here, the plants and
animals exist in balance with each other and
the environment. For example, in New Jersey
a hemlock-beech-maple forest is a climax
community. Animals that reside here include,
chipmunks, deer, bear, turkeys, rabbits,
squirrels, fox, birds, to name a few!
Typical New Jersey State forest
Animals in a hemlock, beech, maple forest
Animals found in a TYPICAL New Jersey
State forest
Climax communities are stable
• The climax community will exist indefinitely
without further change, unless something
catastrophic occurs. A volcanic eruption or a
forest fire, will alter and possibly destroy the
climax community. Then, ecological succession
begins again and after many years, a new
climax community will develop.
Secondary Succession
• Begins in a place that already has soil and was
once the home of living organisms
• Occurs faster and has different pioneer
species than primary succession
• Example: after forest fires
Secondary succession
• SECONDARY SUCCESSION begins in habitats where communities were
entirely or partially destroyed by some kind of damaging event.
• When an existing community has been cleared by a disturbance such as
a fire, tornado, etc...and the soil remains intact, the area begins to return
to its natural community. Because these habitats previously supported
life, secondary succession, unlike primary succession, begins on
substrates that already bear soil. In addition, the soil contains a native
seed bank.
• Since the soil is already in place, secondary succession can take place five
to ten times faster than primary succession.
Why Does Ecological Succession
Occur?
• Organisms alter their environment
• Organisms become less suitable for
environment
• New organisms better adapted to changes in
the environment come in and out compete
original organisms
A Summary of Changes That occur During
Succession
• Pioneer species colonize a bare or disturbed site. Soil building.
• Changes in the physical environment occur (e.g., light, moisture).
• New species of plants displace existing plants because their seedlings are
better able to become established in the changed environment.
• Newly arriving species alter the physical conditions, often in ways that
enable other species to become established.
• Animals come in with or after the plants they need to survive.
• Eventually a climax community that is more or less stable will become
established and have the ability to reproduce itself.
• Disturbances will start the process of succession again.
Does Ecological Succession
Ever Stop?
• No
• Do Humans Affect
Ecological Succession?