Transcript Chapter 13: Principles of Ecology Section 13.2

Chapter 13: Principles of Ecology
Section 13.2
Biotic and Abiotic Factors
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Objectives
• To be able to identify biotic and abiotic
elements in an ecosystem.
• To be able to describe how a change in one
element in an ecosystem can affect others.
• To be able to compare and contrast how
ecosystems have been altered due to changes
in biotic and abiotic changes.
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Starter
• I would like you to imagine yourself first in a
woodland then in a desert.
• Now, I want you to pick up a handful of soil in
each place. What differences would you find?
• Woodland soil is rich in organic matter and
holds water well. The desert’s sandy soil has
little organic matter and does not hold water.
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Ecosystem – Biotic and Abiotic
• Ecosystems are made up of living and nonliving components.
These components are
referred to as biotic
and abiotic factors.
While they are
considered separate,
they act upon one
another in complex
ways.
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Ecosystem – Biotic and Abiotic
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Biotic Factors
• Biotic factors are living things, such as plants,
animals, fungi, and bacteria.
– Each organism plays a particular role in the
ecosystem.
– Ex. fungi breakdown organic material, earthworms
enriching the soil, methane consuming Achaea,
turkey vultures consuming carrion, wolves hunting
moose, etc.
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Biotic Factors
Wolves
hunting
moose
on Isle
Royale
in Lake
Superior
A methane consuming deep
sea Achaea
Turkey Vulture
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Abiotic Factors
• Abiotic Factors – nonliving things such as
water, temperature, pH, wind, sunlight,
minerals, and soil.
– The balance of these factors determines which
living things can survive in a given environment.
– Changes in only one abiotic factor can reverberate
throughout an ecosystem – causing species to
disappear or go extinct and other species to
invade.
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Abiotic Factors
• Example: Coral Bleaching.
Triggered by changes in temperature, pH,
salinity, and light. Corals are very
sensitive to climate change and we are
seeing huge die offs and extinctions.
Coral reefs are the tropical rainforests of
the seas - they are second only to
rainforests in terms of biodiversity.
Major source of protein for humans all
around the world.
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Abiotic Factors
• Acidification of the oceans due to greater
concentrations of carbon dioxide.
Carbon dioxide reacts with
water to form carbonic acid.
Acidification of the oceans is
a major problem because
animals depend on pH being
constant, otherwise they
cannot survive.
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What are the abiotic and the biotic factors that you see in
this photo of a beaver dam? How do they interact?
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What are the abiotic and the biotic factors that you see in this photo
of a beaver dam? How do they interact? (same question as last slide)
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Keystone Species
• A keystone species is a species that has a
disproportionately large effect on
its environment relative to its abundance.
• They play a critical role in maintaining the
structure of an ecological community - affecting
the majority of organisms in a community.
• They have a large impact in determining the
types and numbers of other species in the
community.
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Example: Salmon
• What role do Pacific salmon play in their
ecosystems?
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Salmon and their ecosystem
• Over 140 species utilize the Pacific salmon for
food.
• If not eaten, then their bodies decay and
return essential nutrients to the rivers where
they spawn.
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An ecosystem at risk . . .
• Due to profound changes to their
environment, 214 species of Pacific salmon
(and relatives like steelhead) are threatened
with extinction – 106 are already extinct.
– Population declines due to:
1. Dams (unable to reach spawning grounds).
2. Polluted rivers from mining, logging and other
industries.
3. The commercial salmon industry.
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Biodiversity Concept
• Bio – life
• Diversity - the quality or state of
having many different forms or
types.
• Put the two together and you
have a measure of the diversity
of life (the number of species) in
a given ecosystem.
E.O. Wison –
developed the
concept of
biodiversity
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Biodiversity
• Biodiversity is the assortment, or variety, of
living things in an ecosystem.
– For example: a rain forest, like the Amazon
rainforest) has a large assortment of different
species living in proximity to one another. A
desert, on the hand is poor in biodiversity (there
are a lot fewer species living in a desert
ecosystem).
– Two factors that influence biodiversity are rainfall
and temperature. More rainfall, like in the rain
forest, are linked with greater biodiversity.
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Biodiversity
Which of these two ecosystems
contains the most distinct, different
habitats?
Which has more niches?
Given what you know about biodiversity, in
which of these two ecosystems would you
find more biodiversity?
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Biodiversity and Keystone Species
• Keystone species concept and biodiversity are
intimately linked.
• Keystone species are responsible for causing
greater biodiversity in their ecosystems.
– When a keystone species is removed (example
beavers, wolves, and bison), the biodiversity of
the ecosystem suffers significantly.
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Example: Bison
How are bison like Pacific salmon?
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Bison, the center of their ecosystem
The bison were (and hopefully will be again) the
prairie’s keystone species. They were hunted
nearly to extinction.
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Video – Wolves of Yellowstone
• This video ties all of the concept we have been
studying together.
– Research – field work and application of science.
– Biotic and abiotic factors
– Populations, communities, ecosystems, etc.
– Keystone species
– Biodiversity
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Yellowstone Video Review
• How did the Yellowstone ecosystem change with
the reintroduction of the wolves?
– What was the condition of the park’s habitat (range)
before wolf reintroduction?
– How did the park’s habitat change after there
reintroduction?
• What role do wolves play in the Yellowstone
ecosystem?
– How do the wolves affect the other parks species?
• Why do we call them a keystone species?
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