Transcript UNIT 4 – ECOLOGICAL STUDIES I. INTRODUCTION

UNIT 4 – ECOLOGICAL
STUDIES
I. INTRODUCTION TO
ECOLOGY
(pp. 63, 64, 98-104)
Founder of Ecology
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Ernst Haeckel – “Oikos”
A. Introduction
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Ecology is the study of interactions
between organisms and their
environment; therefore the study of
ecology includes biotic, or _living_
factors, as well as abiotic
(non-living_) factors.
B. Levels of Organization
1. _Species______ - a group of similar
organisms that can interbreed and
produce fertile offspring
B. Levels of Organization
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2. _Population__ - a group of organisms that belong
to the same species and live in one area. The area in
which an organism lives is known as its _habitat_.
3. __Community_ - many different species of
organisms living in the same _habitat_
4. _Ecosystem_ - a community and the _abiotic_
factors that affect it
5. _Biome____ - a group of ecosystems that have
the same climate and similar _communities_
6. _Biosphere_ - Earth
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II. “THE STUDY OF . . . “
Ecologists spend large amounts of time
investigating interactions between _biotic_ and
_abiotic_factors. It is important that ecologists
have an understanding of experimental design.
An experimental design that is flawed does not
produce valid results or justifiable _conclusions.
A. Laboratory Investigations - There are a variety of
ways to conduct a laboratory investigation depending on
the desired outcome.
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1. Comparative – A _comparison_____ of two or
more things; for example, comparing plant cells with
animal cells under the microscope
2. Descriptive – Observational lab in which
quantitative (_involve numbers, measurements,
quantities__) and qualititative (_descriptions__)
information is obtained; for example, Seed Journal
3. Experimental – Designed experiment that follows
the _scientific method____. Clearly defined
_control___and test group(s).
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B. The Scientific Method (pp.3-15)
The term, “scientific method” is
misleading because it actually refers to a
process that is neither reserved for
ecologists and other scientists, nor a
methodical set of steps to be followed in a
specific order. Instead, it is an
_organized__ pattern of thinking to solve
everyday problems.
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The Scientific Method - “How dull!”,
you might say
But it’s actually a tool we use
everyday
To shop and compare and problemsolve, too
It’s just a pattern of thinking in much
that we do!
III. A CLOSER LOOK AT THE
SCIENTIFIC METHOD
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A. _Question or Problem__
B. Forming a _hypothesis__
A hypothesis is a TESTABLE
explanation or prediction
C. Setting Up a Controlled
_Experiment_
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To test a hypothesis or find an answer to
a question, a scientist will usually set up a
controlled experiment. A controlled
experiment usually consists of two groups:
1. Control – Set-up used as a
_benchmark or standard for comparison_
Experimental Group
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2. Experimental Group – Group in which all
conditions are kept the same except for a _single
variable__. A variable is a _factor changed by the
experimenter__. Only _one__ factor should be changed
in each experimental group. This change is designed to
_test the hypothesis.
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a. Manipulated (independent) variable – factor that
is _changed by the experimenter__
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b. Responding (dependent) variable – condition
that is measured or observed as a result of the change
D. Collecting Data
Data from an experiment should be
presented in a concise and organized
manner. Often _graphs___ are used as a
visual representation of the results. The
types of graphs used most often to
illustrate results are:
1. _Circle (Pie)_ Graph – Used to show
relationship of a part to a whole
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Graphs
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2. _Bar_ Graph – Used when independent variable
isn’t continuous; for example, absorbency of different
brands of paper towels
3. _Line__ Graph – Used when _independent____
variable is continuous; for example, time. A line
graph most clearly shows the relationship between the
independent & dependent variables in an experiment. In
a line graph, the manipulated (independent)
variable is plotted on the _X__ axis and the
responding (dependent) variable is plotted on the
_Y__ axis.
Where does distance go?
Manipulated (Independent) Variable:
_______MIX___________________
Responding (Dependent) Variable:
________DRY__________________
E. Analysis and Conclusion
After collecting data, a scientist must
analyze the data and form conclusions
based on the following questions:
1. Do the results _support___ or _refute__
the _hypothesis_?
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Analysis and Conclusion
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2. Is the experimental set-up _valid___?
a. Was there a large enough _sample size___?
b. Although no experimental set-up can be
perfect, were the _sources of error_ minimized?
c. Was there only _one variable___ tested?
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3. Is the experiment _repeatable__?
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F. Constructing a Theory
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A scientific theory is an explanation
that has been _tested__ many times by
many different _scientists_.
Although a theory has been confirmed by
repeated experiments, it may eventually
be disproven.
IV.
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ENERGY FLOW (pp. 67-73)
All living things require energy. The ultimate
source of energy for the earth is the _sun___.
A. Autotrophs – “_Self-feeder____”. They
are also known as _producers__. Most
producers capture energy from the sun in a
process called _photosynthesis_. Photosynthesis
takes place in the_chloroplasts_ of plant cells.
The equation for photosynthesis is_CO2 +
H2O + light energy → C6H12O6 + O2___.
Photosynthesis
B. Heterotrophs – Organisms that have to _obtain
food_ are called heterotroph or _consumers____.
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There are several categories of consumers:
1. Herbivores – Eat _plants (producers)__
2. Carnivores – Eat _animals (other consumers)__
3. Omnivores – Eat _plants & animals_____
4. Detritivores – Obtain energy from _dead
bodies of
plants and animals; for example, _worms,
vultures, _
5. Decomposers – Break down _organic__
matter. Most
decomposers are in Kingdom _Eubacteria or Kingdom _Fungi_.
C. Energy in a Cell
C. Energy in a Cell – All organisms
(_producers_and _consumers_) must convert
chemical__ energy present in _glucose_ and
other food molecules into usable energy. This
conversion process is known as _metabolism__
and the end-product is a re-chargeable “battery”
used by all cells for energy known as _ATP___.
Most ATP is produced through the process of
_cellular respiration_.
 The equation for cellular respiration is
_ C6H12O6 + O2 → CO2 + H2O +ATP__.
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IV. ENERGY FLOW – A COMPARISON OF
PHOTOSYNTHESIS & CELLULAR RESPIRATION
(p. 232)
PHOTOSYNTHESIS
CELLULAR
RESPIRATION
Function
Use energy from sun to
make glucose
Release energy from
glucose to make ATP
Cell Location
Chloroplasts
Mitochondria
Occurs In
Autotrophs
Heterotrophs AND
Autotrophs
Reactants
CO2 + H2O + energy
C6H12O6 + O2
Products
C6H12O6 + O2
CO2 + H2O + energy
Overall Reaction
CO2 + H2O + energy →
C6H12O6 + O2
C6H12O6 + O2 → CO2 +
H2O + energy
C. Tracing Energy Flow
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A. Trophic Levels - Each step in the pathway of
energy flow is known as a __trophic level_. The first
trophic level is always a ___producer____. The 2nd trophic
level is known as the primary (1 o) _consumer_ and may be
an _herbivore__ or _omnivore_. The last step is always a
_decomposer_.
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1. Food Chains – A food chain illustrates
how energy is transferred by showing _feeding
relationships between organisms. The arrows
show the direction of _energy transfer – means
“is eaten by”_.
Energy flows through an ecosystem in a
series of steps in which organisms transfer
energy by being eaten
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CONSUMERS
(Heterotrophs)
↑
↑
PRODUCERS
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(Autotrophs)
FOOD CHAIN
= _________________
http://fig.cox.miami.edu/Faculty/Dana/foodchain.jpg
Typical Food Chain
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Energy (Sun)________ → __Producer____ →
_1˚ Consumer (herbivore or omnivore)____ →
_2˚ Consumer (carnivore or omnivore)____ →
_Decomposer_
EX: Sun-> Grass->Grasshopper->Mouse->Snake->Hawk
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·Which organism acts as a secondary consumer?
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·According to this food chain, which organism could be
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described as an herbivore?
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·Which organism is the producer?
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·What are two terms that could be used to describe the hawk?
Food Webs
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2. Food Webs – Typically feeding relationships
are more complex than illustrated in a food chain.
Most organisms eat _a variety of organisms and
_are eaten by a variety of organisms. These
interconnected pathways are more accurately
shown in a food web.
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According to this food web . . .
·How many different producers are there?
·Is the grasshopper a producer, primary, or secondary consumer?
·Is the grasshopper an herbivore, carnivore, or omnivore?
·What organism(s) acts as the decomposer?
·Give an example of an organism in this food web that acts as secondary and tertiary consumer.
·If all the squirrels in the community perished, would the hawk be able to survive? Explain.
·If the grass was destroyed, which organism would be most directly affected? Explain.
Ecological Pyramids
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3. Ecological Pyramids – Although in theory, a
food _chain_ or food _web_ can consist of
unlimited numbers of _trophic levels_, in
actuality this does not take place. On average,
only 10%_ of the energy stored in an organism is
passed to the next trophic level. _90% of the
energy is either used by the organism to maintain
_homeostasis_or lost as _heat_to the
environment. Because of this, most food chains
typically consist of only _3 or 4 trophic levels.
Ecologists use _pyramids to represent the
amount of _energy_or _matter_at each _trophic
level.
V. NUTRIENTS IN AN ECOSYSTEM
(pp. 74-80)
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Unlike energy from the sun, nutrients are only
available to an ecosystem in specific quantities
and must be recycled_ within and between
ecosystems. Nutrients may become a _limiting
factor when they are depleted.
Organisms require nutrients to _build
biomolecules, cells, tissues, etc. Although all
nutrients, including _water, are re-cycled, there
are a few nutrient cycles that are especially
important.
A. Water Cycle
B. Carbon Cycle
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Organisms require carbon to make _carbohydrates,
_lipids_, _proteins_, and nucleic acids. Carbon dioxide in
the atmosphere is taken up by _plants____ and
_algae___ for _photosynthesis____. (Algae are
autotrophic, unicellular organisms with cell walls made of
cellulose and chloroplasts that belong to kingdom
_Protista_).
They produce glucose for _cellular respiration___.
Humans and other _consumers___ eat plants & algae, or
they eat other organisms who have eaten plants &
algae. The carbon from glucose is returned to the
atmosphere as _CO 2____, a waste product of cellular
respiration. In addition, erosion, burning of _fossil fuels,
Carbon Cycle
4 main CARBON reservoirs in BIOSPHERE
1.In ____________
atmosphere
as CO2 gas
ocean
2.In _______
as dissolved CO2 gas
3.On _______
in organisms, rocks, soil
land
Underground as coal & petroleum (fossil
4.__________
fuels) and calcium carbonate in rocks
CO2 in
atmosphere
Where does CO2 in atmosphere come from?
1. Volcanic activity
2. Human activity (burning fossil fuels)
3. Cellular respiration
4. Decomposition of dead organisms
CO2 in
Ocean
BIOLOGY; Miller and Levine; Prentice Hall; 2006
C. Nitrogen Cycle
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Nitrogen Cycle – Organisms require nitrogen to build _proteins
and nucleic acids.
The _atmosphere__ is mostly nitrogen, but only _bacteria_
produce the _enzymes_ needed to convert nitrogen from
the atmosphere to a useable form, a process known as
_nitrogen fixation. After nitrogen fixation is carried out by
bacteria in soil, the nitrogen compound in the soil is then
absorbed by _plants__ and used to make _proteins &
nucleic acids_. When other organisms _eat plants and
algae_, they can re-use the nitrogen to build their own
proteins_ and _nucleic acids_. When organisms die,
_decomposers_ return the nitrogen to the soil where it may
be taken up by _plants again or returned to the
atmosphere by other _bacteria_.
Nitrogen Cycle
Nitrogen Cycle
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79% of the atmosphere is made up of
NITROGEN gas (N2)
BUT we can’t use the nitrogen gas we breathe!
The bond in N2 gas is so strong it can only be
broken by:
lightning
Volcanic Activity
Specialized bacteria
D. Phosphorus Cycle
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D. Phosphorus Cycle - All organisms require
phosphorus for DNA, RNA, lipids, and the
phospholipid bilayer of the cell membrane.
Phosphorus is found in soil and rocks, absorbed
by the roots of plants, where it is transported
through the rest of the plant by the xylem.
Consumers eat plants, which is then returned to
the soil
Phosphorus Cycle
E. Nutrient Limitation
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E. Nutrient Limitation – When nutrients are
scarce in an ecosystem, they are described as
limiting nutrient.
This imposes restrictions on the number of
organisms, an organism’s growth, and the
primary productivity of the system.
For example, run-off from fertilized fields can
trigger algae blooms in aquatic systems.
Algla Blooms
VIII. ECOLOGICAL SUCCESSION
(pp. 94-97)
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Ecosystems are constantly changing in response
to natural and human disturbances. As an
ecosystem changes, older inhabitants gradually
die out and new organisms move in, resulting in
further changes in the community. Ecological
succession refers to a series of slow changes
that occur in a physical environment over time.
A. Primary Succession
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A. Primary Succession – Occurs
following destruction of an ecosystem; for
example, after Volcanic eruption, glaciers
melting:
First species to populate area known as
pioneer species
Lichens: Pioneer Species
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Lichens are the most common pioneer
species after a volcano because they are
capable of growing on bare rock. A lichen
is a fungus and cyanobacteria living
together. Cyanobacteria are
photosynthetic bacteria. In a lichen, the
cyanobacteria provides food for the
fungus and the fungus provides water and
protection for the cyanobacteria.
Primary Succession
B. Secondary Succession
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B. Secondary Succession – Occurs
when a disturbance of some kind changes
an existing community without removing
the soil; for example, wildfire, clearing
land, plowing for farming.
Secondary Succession
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ECOSYSTEM INTERACTIONS
(pp. 90-93)
Ecosystems are influenced by a combination of
biological and physical factors. Together biotic
factors and abiotic factors determine the health
of an ecosystem and its _inhabitants_.
The Niche
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A. The Niche - The role an organism plays in its
_community is its _niche. An organism’s niche is
comprised of _biotic_and _abiotic_factors, for
example, the type of food it eats, how it obtains
its food, the way it is food for other organisms,
how & when it reproduces, its physical living
requirements to survive, etc.
Warbler’s Niche
http://www.electricwomen.com/hunterspoint/images/21-street-sign-moreell.jpg
HABITAT vs NICHE?
Habitat is like an
organism’s
address
____________
Jellystone Park
Niche is like an
OCCUPATION
organism’s ______________
http://resmedicinae.sourceforge.net/logos/doctor.png
http://www.michcampgrounds.com/yogibears/yogi-picnic-cartoon.jpg
http://www.formaui.org/kamalii/critters.htm
B. Interactions Within a Community
Community interactions have a powerful effect on
an ecosystem:
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Competition – Competition occurs when
organisms are attempting to use the same
_resources at the same time. Each different
species within a community must have its own
_niche_.
NO TWO SPECIES CAN
SHARE THE SAME NICHE IN THE SAME HABITAT !
Competitive exclusion principle
= ______________________________
BIOLOGY; Miller and Levine; Prentice Hall; 2006
Predation
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2. Predation – The organism that
does the killing and eating is the
_predator and the food organism is
the _prey_.
3. Symbiosis – A relationship in which two
organisms _live very closely together is described
as symbiosis.
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There are three main types of symbiotic
relationships:
a. Mutualism – Both organisms _benefit. For
example, virtually all plant roots have
mycorrhizae – a Fungus that resides within the
plant roots. Fungus enhances absorption of
water and nutrients in roots; plant provides
protection for the fungus.
Commensalism
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b. Commensalism – In commensalism, only one
organism benefits, but the other organism _is not
harmed.
For example, barnacles are small _animals_that
often attach themselves to whales. They do not
harm the whales, and the barnacles benefit from
the _movement of water as whale swims –
provides food for barnacles.
Friendship
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c. Parasitism – In parasitism, only
one organism benefits and the other
organism is _harmed__ by the
relationship. The organism that is
harmed is known as the _host__.
Examples of parasites include
_tapeworms, hookworms, ticks, lice.
V.
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POPULATIONS WITHIN AN ECOSYSTEM
(pp. 124-127)
Populations within an ecosystem cannot have
unlimited growth. There are conditions that have
an impact on population size known as _limiting
factors. Limiting factors may described as
density-dependent or density-independent.
A. Density-Dependent Limiting Factors
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A. Density-Dependent Limiting Factors –
Density-dependent factors depend on population size;
For example, _competition__ and availability of _food___,
_water__,_sunlight, shelter & mates. Diseases and
crowding.
War, famine and
disease for humans
B. Density-Independent Limiting
Factors
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B. Density-Independent Limiting Factors– These are factors
that affect all populations the same way,
regardless of size. Examples include _unusual weather,
natural disasters__, and human activities such as _cutting
down trees, damming rivers, etc…
SHORT SUPPLY
If a nutrient is in _____________
CYCLES SLOWLY
OR __________________
it will LIMIT the growth of the
population
LIMITING FACTOR
= _____________
During this drought,
there was not enough food
available and many kangaroos
and cattle starved.
http://www.wspa-international.org/exhibition/gallery/large_DeadKenyan%20droughtSPANA.jpg
C. Climax Community
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C. Climax Community– A climax community is a
_stable community with very little population
growth or decline. Each ecosystem has a
_carrying capacity_, a certain number of
organisms that can exist _successfully_. When
the carrying capacity is exceeded, resources
become a _limiting factor_, and population
numbers _decline_.