Energy in Ecosystems
Chapter 13, Unit 13.3
Objectives
• To describe the roles of producers and
consumers in ecosystems.
• To apply the concept of producers and
consumers to your own life.
• To compare photosynthesis to
chemosynthesis.
Main Ideas
• Producers provide energy for other organisms
in an ecosystem.
• Almost all producers obtain their energy from
sunlight.
Chlorophyll Abundance on Earth
Biodiversity
• One of the most important concepts in
ecology and all of science!
• It is an expression of the energy and richness
of an ecosystem.
• Note on the previous map, the ecosystem
with the most biodiversity lie around the
equator, where you find the greatest
concentration of sunlight.
Biodiversity
• Biodiversity is the result of millions of years of
evolution – new species are born as species
adapt to their environment and are modified
over time by natural selection.
– Adaptation leads to, over time, speciation, which
means one species splits into two (becoming
reproductively isolated) or more new species.
• Biodiversity – bio means life and diversity
means variety. Literally it means the
diversity of life.
Wild Canine Adaptations and
Diversity
Biodiversity
• It is what supports food webs and ecosystem.
– As an ecosystem loses its biodiversity, it becomes
impoverished and, if it loses its keystone species,
it can collapse altogether (remember the coral,
sea otters, and wolves).
• It is conservatively estimated that, worldwide,
three species go extinct every hour – almost
all due to human caused ecological changes.
Centinela – a Case in Point
• In the Andean foothills of Ecuador, there is a
ridge called Centinela.
– It is a symbol of the silent destruction of
biodiversity.
– When the forest on Centinela was cut, many rare
species, only recently discovered by botanists,
were reduced from healthy populations to
extinction.
– Unfortunately, this is too common and dangerous
for us – our world loses its living buffer.
Centinela
• Centinela burning
Important Vocabulary
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Producer
Autotroph
Consumer
Heterotroph
Chemosynthesis
Photosynthesis
You will have to know what these mean!
Photosynthesis
• An equation that is the key to life:
– 6H2O + 6CO2
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C6H12O6 + 6O2
What vital process does this formula denote?
Answer: Photosynthesis.
Why does life as you know it depend on this
formula?
Answer: Photosynthesis captures the sun’s energy
and transforms it to chemical energy, which can be
used by other organisms (including us).
Sunlight
The Flow of Energy
• We learned about biotic and abiotic factors in
our last unit (13.2). Another important part of
an ecosystem is the flow of energy to fuel life
processes in all organisms.
– Breathing and growing.
• We are going to find out where the energy
comes from and what role it plays within an
ecosystem.
The Flow of Energy
• Producers – are organisms that get their
energy from nonliving resources.
– in other words THEY MAKE THEIR OWN FOOD
– Producers are also called autotrophs.
• -troph is a suffix that comes from the Greek word
meaning “nourishment.”
• Auto- is a prefix and means “self”
• Autotroph, put together means self-nourishing.
The Flow of Energy
• Consumers – organisms that get their energy
by eating other living things (plants and
animals).
• Consumers are also called Heterotrophs
– Hetero- means “different,” so heterotroph literally
means different-nourishing (in other words, they
get nourishment from other organisms).
Examples of Autotrophs
All ecosystems depend on producers. These
photos are of producers: redwood trees in
California, tropical rainforest trees in the
Amazon, and phytoplankton which help to fuel
aquatic fresh and salt water ecosystems.
Examples of Heterotrophs
All these animals are heterotrophs. In the
upper left corner are our Yellowstone wolves,
then a blue jay, a krill (a small marine
shrimp), and a blue whale (the largest
creature to have lived on Earth and a
consumer of krill, which they filter from the
sea through their baleen).
A Simple Food Chain
• We will talk more about life webs and
pyramids in the next unit but a simple one is:
This is a very simple food
chain from the very cold
waters of Antarctica.
• The producer is the
phytoplankton.
• Krill (small shrimp) eat
the phytoplankton.
• The blue whale eats the
krill.
Almost all producers use sunlight
• Almost all producers obtain their energy from
sunlight – driving the photosynthesis.
– Photosynthesis is a two step process in which
green plants, cyanobacteria, and some protists
form carbohydrates from the reaction of carbon
dioxide and water.
– Energy is stored by the producers as
carbohydrates for powering their metabolism.
– Oxygen is the waste product of photosynthesis,
which is very lucky for us!
Question in Transit
• Q: What would happen to a forest ecosystem
if it is clear cut?
• A: Primary consumers would die out or have
to migrate to a new location - that might not
exist, or is not good habitat. Secondary
consumers would have to migrate or die.
Not All Producers Use Light Energy
• Chemosynthesis – is the process by which an
organism forms carbohydrates using
chemicals, rather than light, as an energy
source.
• Chemotrophs are were discovered at deep-sea
vents on the bottom of the ocean (where
there is no sunlight).
– The vents are places where superheated water
shoots out of the ocean floor.
Chemotrophs
• Chemotrophs are tiny prokaryotes which, at
those vents, were found capturing minerals
from the water (replacing sunlight) and
making their own food.
• We have discovered Chemotrophs living in
sulfer-rich salt marsh flats in hydrothermal
pools in Yellowstone National Park (and other
places where there is hydrothermal activity).
Archea are Chemotrophs
• As we have already discussed in class, Archea
are chemotrophs.
• The live in deep sea vents and hydrothermal
pools (like geysers).
• They use minerals available in those hostile
environments as an energy source.
• They date back to the beginning of life on
Earth, before there was oxygen (3.5 billion
years ago).
Review Questions
• Q: How does the stability of an ecosystem
depend on its producers?
• A: Producers bring energy into an ecosystem.
• Q: What are the two processes used by
producers to obtain energy?
• A: Photosynthesis and chemosynthesis
Review Questions Continued
• Few producers live deep below a lake’s
surface, create a hypothesis that explains this
fact.
• A: Sunlight cannot penetrate the water to a
great depth, so photosynthesizing organisms
are more common near the water’s surface.
Review Questions Continued
• Q: Could producers survive without consumers?
Explain why or why not.
• A: Producers do not require consumers to fill
material needs as a food source. Therefore, in that
sense, producers do not need consumers to survive.
However, a lot of producers depend on consumers
for reproduction and survival.
Review Questions Continued
• Q: How might chemosynthetic organisms help
scientists to understand how life developed on
Earth?
• A: Chemosynthetic organisms live in
environments that may be similar to those
that existed on Earth billions of years ago
when life was beginning to develop. Studying
these organisms enables us to create models
of how life forms might have evolved on Earth.