Transcript Ecology Unit

Ecology Unit
What is ecology?
Ecology- the scientific study of
interactions between organisms
and their environments,
focusing on energy transfer
• It is a science of relationships.
What do you mean by environment?
The environment is made up of two
factors:
Biotic factors- all living organisms
inhabiting the Earth
Abiotic factors- nonliving parts of
the environment (i.e. temperature,
soil, light, moisture, air currents)
ABiotic Factors
• Water– Essential to all living things.
• Sunlight– Necessary for
photosynthesis.
• Oxygen– Essential to most living
things.
• Temperature –Determines the type
of organisms in an area.
• Soil– Affects plant growth, shelter,
and bacteria.
Biosphere
Ecosystem
Community
Population
Organism
Organism- any unicellular or
multicellular form exhibiting all of the
characteristics of life, an individual.
•The lowest level of organization
Population-a group of organisms of
one species living in the same place
at the same time that interbreed
and compete with each other for
resources (ex. food, mates, shelter)
Community- several interacting
populations that inhabit a common
environment and are interdependent.
Ecosystem- All living and non-living things
in a given area that interact with one another.
–Can be large or small
Biosphere- life supporting portions
of Earth composed of air, land,
fresh water, and salt water.
•The highest level of organization
“The ecological niche of an
organism depends not only on
where it lives but also on what
it does. By analogy, it may be
said that the habitat is the
organism's ‘address’, and the
niche is its ‘profession’,
biologically speaking.”
Odum - Fundamentals of Ecology
Habitat vs. Niche
Niche - the role a species plays in
a community (job)
Habitat- the place in which an
organism lives out its life
(address)
Habitat vs. Niche
A niche is determined by the
tolerance limitations of an
organism, or a limiting factor.
Limiting factor- any biotic or
abiotic factor that restricts the
existence of organisms in a
specific environment.
Habitat vs. Niche
Examples of limiting factors-
•Amount of water
•Amount of food
•Temperature
Part 2: Energy Pathway in
Aquatic Ecosystems:
• The flow of energy through an
ecosystem begins with the sun, and is
passed on through various organisms:
• The energy of the sun begins the flow of
energy for living
Sun  Producers  Consumers  Decomposers
Energy Pathway
• Producer- autotrophic
organisms that are able to make
their own food. Most producers
perform photosynthesis
(making food from the sun) or
chemosynthesis (making food
from inorganic compounds).
• Examples: aquatic plants,
algae, phytoplankton
Energy Pathway
• Consumerheterotrophic organisms
that get energy by eating
producers or other
consumers.
• Examples: aquatic
invertebrates, fish
• Carnivores
• Omnivores
More Secondary Consumers
• Carnivores – eat meat
• Invertivores – eat
invertebrates
• Planktivores – eat
zooplankton
• Omnivores – eat lots of
things
Higher Level Consumers
Consumers can be at different levels, depending on
the specific food chain.
Energy Pathway
Decomposers – obtain
energy from the remains
of other organisms.
Decomposers are most
important for the
recycling of matter
within ecosystems.
Examples: crabs, lobsters,
bacteria
Types of Consumers
Primary Consumers
First level of consumers that
eat producers These are all
herbivores (or planteaters)
Ex. Zooplankton, some
aquatic invertebrates,
some fish
Types of Consumers
Secondary consumers
Second level of
consumers that eat
primary consumers.
These are carnivores
(meat eaters),
invertivores (eat
invertebrates),
planktivores (feed on
zooplankton), or
omnivores (feed on a
variety of things)
Types of Consumers
Tertiary (Top)
Consumers
Higher level consumers
that begin at the
third level or higher.
Tertiary consumers
are usually those at
the top of the food
chain in that
ecosystem.
Ex. Bass, turtles,
snakes, alligators
Types of Consumers
Decomposers
Detritivores – heterotrophic
organisms that get energy by
shredding and eating detritus
(non-living organic matter, ie:
bodies of dead things). These
are the scavengers of aquatic
ecosystems.
Examples: most bottom dwelling
organisms
Bacteria and fungi – these
break down remaining
particles into the tiniest units
to release nutrients for use
by producers
Part 3: Feeding Relationships
There are 3 main types of
feeding relationships:
1. Producer- Consumer
2. Predator- Prey
3. Parasite- Host
Symbiotic Relationships
Symbiosis- two species living together
3 Types of
symbiosis:
1. Commensalism
2. Parasitism
3. Mutualism
Symbiotic Relationships
Commensalismone species benefits
and the other is
neither harmed nor
helped
Example: Relationship between
small fish and the pond weeds;
the fish hide between the weeds
from larger fish. Another
relationship is the one between
oysters and the mangrove trees.
The oyster anchor and protect
themselves with the roots of the
tree.
Symbiotic Relationships
Parasitismone species benefits (parasite) and
the other is harmed (host)
• Parasite-Host relationship
• Example:
Freshwater Ich, a
protozoa that infects fish
Symbiotic Relationships
Parasitism- parasite-host
Ex. lampreys,
leeches, fleas,
ticks,tapeworm
Symbiotic Relationships
Mutualismbeneficial to both
species
Example: some small fish
enter & clean the mouths
of larger fish, and in
exchange, they may eat
whatever they clean out.
Cleaner Shrimp
Type of
Species
relationship
harmed
Commensalism
Parasitism
Mutualism
= 1 species
Species
benefits
Species
neutral
Food Chains & Food Webs
All organisms are interconnected by food
chains, and play an important role in
their ecosystem’s food web
Food chain- are the feeding relationships
between individual organisms.
Food Chains & Food Webs
Food webs are all of the interconnecting food chains in an
ecosystem.
A change in the populations of one organism in a food chain
can seriously alter all other organisms of the food web!
Trophic Levels
• Each link in a food chain is known
as a trophic level.
• Trophic levels represent a feeding
step in the transfer of energy
and matter in an ecosystem.
Trophic Levels
A limit is reached when consumers cannot
consume enough energy to balance energy
lost during normal physiological functions
(growth, reproduction). Most ecosystems
have about four to five trophic levels.
• Note: An organism can be at varying trophic
levels (feeding level) of a food web, depending on
the specific food chain you are examining. A
change in the population of one organism or one
trophic level in a food chain can seriously alter
all other organisms of the food web.
Food Web:
• In any ecosystem, most organisms
have more than one source of food.
For example, a large fish may feed on
smaller fish, crayfish, and insects.
This process results in an organism
being part of more than one food
chain. The complex overlapping of
food chains is known as a food web
Food chain
(just 1 path of energy)
Food web
(all possible energy paths)
Part 4: Ecological Pyramids
• Diagrams showing the relative
amounts of energy or matter
contained within each trophic level in
a food chain.
– 3 types
• Pyramid of Energy
• Pyramid of Biomass
• Pyramid of Numbers
Pyramid of Energy
• shows how energy flows through a
food chain from trophic level to
trophic level. Most of the energy an
organism obtains is used for its life
processes (reproduction, respiration,
growth, etc.) Only about 10% is
available to the next higher
organism that eats it.
• The nutritional quality of material
that is eaten also influences how
efficiently energy is transferred,
because consumers can convert
high-quality food sources into new
living tissue more efficiently than
low-quality food sources
E
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Trophic Levels
Tertiary
consumers- top
carnivores
Secondary consumerssmall carnivores
Primary consumers- Herbivores
Producers- Autotrophs
Trophic Levels
Biomass- the amount of organic matter
comprising a group of organisms in a
habitat.
• As you move up a food chain, both
available energy and biomass
decrease.
• Energy is transferred upwards but is
diminished with each transfer.
Part 5: Trophic Levels in an
Ecosystem
How many trophic levels can an ecosystem
support?
• This depends on several factors:
• the amount of energy entering the ecosystem
• energy loss between trophic levels
• the form, structure, and physiology of
organisms at each level.
– Predators at higher trophic levels are generally
physically larger than organisms at lower levels, so
they have to forage over increasingly large areas to
meet their energy needs.
Trophic Levels
• Because of energy losses, most land ecosystems
don’t have more than 5 trophic levels. Marine
ecosystems generally have no more than 7. This
difference is most likely due to the differences
between the producers of these two ecosystems. In
marine ecosystems, microscopic phytoplankton
carry out most of the photosynthesis, while plants
do most of this on land.
Trophic Levels
• Phytoplankton are extremely small with very
simple structures, so most of their primary
energy production is consumed and used for
energy by the primary consumers that feed on
them. Land plants, however, have large
amounts of unusable parts in terms of
providing a source of energy to what eats
them. The roots, trunks, and branches of plants
cannot be used for food (by most organisms),
so less of the energy produced by those plants
travels up the food chain
Biological Magnification in Food
Webs
• An important consequence of the loss of
energy between trophic levels is that
contaminants collect in animal tissues—a
process called bioaccumulation, or
biological magnification. As contaminants
bioaccumulate up the food web, organisms
at higher trophic levels can be threatened
even if the pollutant is introduced to the
environment in very small quantities.
Biological Magnification
• The insecticide DDT, which was widely
used in the United States from the 1940s
through the 1960s, is a famous case of
bioaccumulation. DDT built up in eagles
and other large predatory birds to levels
high enough to affect their reproduction,
causing the birds to lay thin-shelled eggs
that broke in their nests. Fortunately,
populations have rebounded over
several decades since the pesticide was
banned in the United States. However,
problems persist in some developing
countries where toxic bioaccumulating
pesticides are still used.
Biological Magnification
• Bioaccumulation can threaten humans as
well as animals. For example, in the United
States many federal and state agencies
currently warn consumers to avoid or limit
their consumption of large predatory fish
that contain high levels of mercury, such as
shark, swordfish, tilefish, and king
mackerel, to avoid risking neurological
damage and birth defects.