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Ecology
Interactions in the Environment
What is Ecology?
• The science of ecology includes everything
from global processes (above), the study
of various marine and terrestrial habitats
(middle) to individual interspecific
interactions like predation and pollination
(below).
Ecology is…
• the study of the interactions
between living organisms and
their biotic and abiotic
environments.
• Ecology is therefore the study
of the relationship of plants and
animals to their physical and
biological environment.
An environment is characterized by
the ABIOTIC and BIOTIC factors.
• Abiotic factors are non-living.
• Abiotic factors include science like chemistry, physics and geology.
• Interactions of abiotic factors result in weather, seasonal changes, tides, air
quality, and water quality
• Biotic factors are living and can be categorized within an
Species
ecosystem structure…
Population
Community
ECOSYSTEM: all of the communities that live in an area together
with the abiotic factors in the environment
Biotic features are all living things in the
biosphere.
• The biosphere is all the parts of
Earth that support life.
• This measures approximately
20km thick (12.4 miles). Most life
on Earth exists between 500m
below the surface of the ocean
and about 6km above sea level.
• How are biomes and ecosystems related?
• Biomes are large regions of the world with similar plants,
animals, and other living things that are adapted to the climate
and other conditions. Explore the links below to learn more
about different biomes. A biome is made of many similar
ecosystems.
What types of
communities make
up these ecosystems?
What types of abiotic
factors are influencing
these ecosystems?
Abiotic and Biotic factors are
intimately intertwined…. Geographic
location (latitude and longitude)
determines abiotic factors such as
temperature and climate….which in
turn, dictates or forces a certain type
of ecosystem to exist.
Levels of
Organization
studied in
Ecology…
An organism’s niche
• Habitat: the actual place an
organism lives
• Niche: both living and non-living
parts of an ecosystem that
determines an organism’s role
in the ecosystem.
• If two species share the same
niche, they will have various
interactions.
• How can species interact?
• These relationships are complex. Each population
of species interacts with other species, or biotic
factors, as well as with the all of the abiotic factors.
• The niche of an organism and it’s interactions is
determined by where it stands in the ecological
structure of the ecosystem.
-Producers
-Consumers
-Decomposers
-Scavengers
Producers
• Producers are autotrophic
organisms that make their
own food.
• Phototrophic organisms
use photosynthesis and
contain chlorophyll
(Carbon Dioxide + Water +
Sunlight =Sugar + Oxygen)
• Chemotrophic organisms
use chemicals other than
H20, such as H2S
PRODUCERS
Consumers
Consumers are heterotrophic organisms that cannot
make their own food. They must ingest (eat) other
organisms.
-Herbivores feed on vegetation (producers).
-Carnivores feed on herbivores or on other
carnivores.
Secondary carnivores feed on herbivores,
Tertiary consumers feed on other carnivores
-Omnivores feed on both producers and consumers
-Scavengers feed on dead or decaying organisms
CONSUMERS
Scavengers feed on CARRION (dead or injured
animal corpses) and dead plant biomass.
Scavengers reduce the size of dead organic
matter…Decomposers will finish the job!
DECOMPOSERS are heterotrophs that recycle small,
often microscopic bits of dead organic matter into
inorganic nutrients availbe for plants to take up from the
soil. Decomposers RECYCLE nutrients!
BACTERIA and FUNGI are decomposers…most worms
are plant scavengers
Energy in the Ecosystem
• Plants absorb less than 1% of the sunlight that reaches them!
• However, photosynthetic organisms make 170 billion metric
tons of food each year
• The energy captured by producers is used to make cells in both
producers and consumers.
Trophic levels
• Trophic levels are the
different feeding levels of
organisms in an ecosystem.
Producers are the first trophic
level and consumers make up
several more.
• These relationships can be
seen in an ecological pyramid.
• Biomass: the total amount of
organic matter present in a
trophic level. The biomass in
each trophic level is the
amount of energy- in the form
of food- available to the next
trophic level.
The Ten Percent Law
• Most of the energy that enters through
organisms in a trophic level does not
become biomass. Only energy used
to make biomass remains available to
the next level.
• When all of the energy losses are
added together, only about 10% of
the energy entering one trophic
level forms biomass in the next
trophic level. This is known as the 10
percent law.
MORE Ten Percent Law
• The 10 percent law is the main reason that most food
chains have five or less links. Because 90 percent of
the food chain’s energy is lost at each level, the
amount of available energy decreases quickly.
10 PERCENT
LAW
Heat and Movement
Consumed
Digested
Growth
Not Digested
Waste
Not Consumed
Decomposers
The majority of energy is lost via heat and movement!
Ecological pyramid
Remember
scavengers and
decomposers can
enter at any level!
Tertiary Consumers= CARNIVORE EATING
OTHER CARNIVORES
Secondary Consumers= CARNIVORES
EATING HERBIVORES
Primary Consumers= HERBIVORES
PRODUCERS = Autotrophic Plants
Ecological Pyramids
• Relative amounts of energy are represented in an
ecological pyramid: a diagram that shows the
relative amounts of energy in different trophic
levels in an ecosystem. An ecological pyramid
can show energy, biomass, or the number of
organisms in a food web.
Ecological Pyramid: Energy
Shows the relative transfer of energy (joules) from one
trophic level to the next.
Ecological Pyramid: Biomass
Shows the relative amounts of organic matter (gram) from
one trophic level to the next.
Ecological Pyramid:
Number of Organisms
Shows the relative number of organisms at each trophic level.
Food Chains
A Food CHAIN is a series of
organisms that transfer
food between the trophic
levels of an ecosystem
using only one species at
each level…a simple
chain.
• The arrows represent the
flow of energy from one
organism to the next.
• The arrow points toward
the organism doing the
‘eating’.
Food Webs
Ecosystems are not as
simple as shown and not
often explained by a
single food chain… Food
WEBS more accurately
show the network of
food chains representing
the feeding relationships
among organisms in an
ecosystem.
• Most organisms feed on
more than one type of
organism at different
trophic levels.
Biological Magnification
• BIOLOGICAL MAGNIFICATION
• The concentration of a pollutant in organisms increases at higher
trophic levels in the food web because these chemicals build-up in the
fatty tissues of these organism and do not dissolve or flush-out of the
organism.
• DDT & Mercury examples:
• DDT is a pesticide used to kill insects like malaria-carrying mosquitoes. However,
this chemical will magnify in concentration in larger organisms like birds and
mammals and harm their reproductive abilities.
• Bald eagle populations declined rapidly to the point of extinction as an
endangered species as mother birds were not able to incubate or hatch their eggs
because the eggs shells were too thin and would crush and break when sat upon
to keep warm in the nest.
Biological Magnification
As the living
organisms eats more,
the concentration of
these substances
increases as they pass
from one trophic level
to the next.
The day it Rained
cats…
• A bizarre case of ecological damage from DDT
occurred in Borneo after the World Health
Organization sprayed huge amounts of the pesticide.
The area's geckos, or lizards, feasted on the
houseflies that had been killed by DDT. The geckos,
in turn, were devoured by local cats. Unhappily, the
cats perished in such large numbers from DDT
poisoning that the rats they once kept in check
began overrunning whole villages. Alarmed by the
threat of plague, WHO officials were forced to
replenish Borneo's supply of cats by parachute.
Relationships in the ecosystem
• Predator/Prey: One organism (predator) will actively
hunt and consume another (prey).
• Competition: two or more organisms of same or
different species compete to use the same limited
resources or basic needs
Symbiotic Relationships
• Parasitism: an organism (parasite)
lives in or on another (host) and
feeds on it without immediately
killing it
• Mutualism: a cooperative
partnership between two
species (both benefit)
• Commensalism: a relationship
where one species benefits and
the other remains unaffected
Coevolution
• When two or more species evolve in response to each other, it is called
coevolution.
• Examples of coevolution may be found between predators and
their prey.
• Plants and insects represent a classic case of coevolution — one that is
often, but not always, mutualistic. Many plants and their pollinators are so
reliant on one another and their relationships are so exclusive that biologists
have good reason to think that the “match” between the two is the result of
a coevolutionary process.