UNIT 4 – ECOLOGICAL UNIT 4 – ECOLOGICAL STUDIESSTUDIES

I. INTRODUCTION TO I. INTRODUCTION TO ECOLOGY ECOLOGY

(pp. 63, 64, 98-104)(pp. 63, 64, 98-104)

Founder of EcologyFounder of Ecology

Ernst Haeckel – “Oikos”Ernst Haeckel – “Oikos”

A. IntroductionA. Introduction

Ecology Ecology is the study of is the study of interactions between organisms interactions between organisms and their environment; therefore and their environment; therefore the study of ecology includes the study of ecology includes bioticbiotic, or _, or _livingliving_ factors, as _ factors, as well as well as abiotic abiotic

((non-livingnon-living_) factors._) factors.

B. Levels of B. Levels of OrganizationOrganization

1. _1. _SpeciesSpecies______ - a group of similar ______ - a group of similar organisms that can interbreed and organisms that can interbreed and produce fertile offspring produce fertile offspring

B. Levels of B. Levels of OrganizationOrganization

2. _2. _PopulationPopulation__ - a group of organisms that __ - a group of organisms that belong to the belong to the samesame species and live in one area. species and live in one area. The area in which an organism lives is known as The area in which an organism lives is known as its _its _habitathabitat_. _.

3. __3. __CommunityCommunity_ - many _ - many differentdifferent species of species of organisms living in the same _organisms living in the same _habitathabitat_ _

4. _4. _EcosystemEcosystem_ - a _ - a community community and the and the __abioticabiotic_ factors that affect it _ factors that affect it

5. _5. _BiomeBiome____ - a group of ____ - a group of ecosystemsecosystems that that have the same climate and similar _have the same climate and similar _communitiescommunities__

6. _6. _BiosphereBiosphere_ - Earth_ - Earth

II. “THE STUDY OF . . . “II. “THE STUDY OF . . . “ Ecologists spend large amounts of Ecologists spend large amounts of

time investigating interactions between time investigating interactions between __bioticbiotic_ and __ and _abioticabiotic_factors. It is _factors. It is important that ecologists have an important that ecologists have an understanding of experimental design. An understanding of experimental design. An experimental design that is flawed does experimental design that is flawed does not produce valid results or justifiable not produce valid results or justifiable __conclusionsconclusions..

A. Laboratory Investigations A. Laboratory Investigations - There are a - There are a variety of ways to conduct a laboratory variety of ways to conduct a laboratory

investigation depending on theinvestigation depending on the desired outcome.desired outcome.

1. Comparative1. Comparative – A _ – A _comparisoncomparison_____ of two or _____ of two or more things; for example, comparing plant cells more things; for example, comparing plant cells with with

animal cells under the microscopeanimal cells under the microscope 2. Descriptive2. Descriptive – Observational lab in which – Observational lab in which

quantitativequantitative (_ (_involve numbers, measurements, involve numbers, measurements, quantitiesquantities__) and __) and qualititativequalititative (_ (_descriptionsdescriptions__) __) information is obtained; for example, Seed Journalinformation is obtained; for example, Seed Journal

3.3. ExperimentalExperimental – Designed experiment that – Designed experiment that follows the _follows the _scientific methodscientific method____. Clearly ____. Clearly defined _defined _controlcontrol___and test group(s).___and test group(s).

B. The Scientific Method B. The Scientific Method (pp.3-(pp.3-15)15)

The term, “The term, “scientific methodscientific method” is ” is misleading because it actually refers misleading because it actually refers to a process that is neither reserved to a process that is neither reserved for ecologists and other scientists, for ecologists and other scientists, nor a methodical set of steps to be nor a methodical set of steps to be followed in a specific order. Instead, followed in a specific order. Instead, it is an _it is an _organizedorganized__ pattern of __ pattern of thinking to solve everyday problems. thinking to solve everyday problems.

The Scientific Method - “How The Scientific Method - “How dull!”, you might saydull!”, you might say

But it’s actually a tool we use But it’s actually a tool we use everydayeveryday

To shop and compare and To shop and compare and problem-solve, tooproblem-solve, too

It’s just a pattern of thinking in It’s just a pattern of thinking in much that we do!much that we do!

III. A CLOSER LOOK AT III. A CLOSER LOOK AT THE SCIENTIFIC METHODTHE SCIENTIFIC METHOD

A. _A. _Question or ProblemQuestion or Problem____ B. Forming a _B. Forming a _hypothesishypothesis____ A hypothesis is a A hypothesis is a TESTABLE TESTABLE

explanation or predictionexplanation or prediction

C. Setting Up a Controlled C. Setting Up a Controlled __ExperimentExperiment__

To test a hypothesis or find an To test a hypothesis or find an answer to a question, a scientist will answer to a question, a scientist will usually set up a controlled usually set up a controlled experiment. A controlled experiment experiment. A controlled experiment usually consists of two groups:usually consists of two groups:

1. Control 1. Control – Set-up used as a – Set-up used as a __benchmark or standard for benchmark or standard for comparisoncomparison__

Experimental GroupExperimental Group 2. Experimental Group 2. Experimental Group – Group in which all – Group in which all

conditions are kept the same except for a conditions are kept the same except for a __single single variablevariable____. A . A variable variable is a _ is a _factor changed by factor changed by the experimenterthe experimenter__. Only ___. Only _oneone__ factor should be __ factor should be changed in each experimental group. This changed in each experimental group. This change is designed to _change is designed to _test the hypothesistest the hypothesis. .

a. Manipulated (independent) variable a. Manipulated (independent) variable – – factor that is _factor that is _changed by the experimenterchanged by the experimenter____

b. Responding (dependent) variableb. Responding (dependent) variable – –

condition that is condition that is measured or observed as a measured or observed as a result of the changeresult of the change

D. Collecting DataD. Collecting Data

Data from an experiment should be Data from an experiment should be presented in a presented in a concise concise and and organizedorganized manner. Often _ manner. Often _graphsgraphs___ ___ are used as a visual representation of are used as a visual representation of the results. The types of graphs used the results. The types of graphs used most often to illustrate results are:most often to illustrate results are:

1. _1. _Circle (Pie)Circle (Pie)_ Graph_ Graph – Used to – Used to show relationship of a part to a wholeshow relationship of a part to a whole

GraphsGraphs

2. _2. _BarBar_ Graph_ Graph – Used when independent – Used when independent variable isn’t continuous; for example, absorbency variable isn’t continuous; for example, absorbency of different of different

brands of paper towelsbrands of paper towels 3. _3. _LineLine__ Graph__ Graph – Used when _ – Used when _independentindependent____ ____

variable is continuous; for example, time. A variable is continuous; for example, time. A line line graph most clearly shows the relationship graph most clearly shows the relationship

between the independent & dependent variables in between the independent & dependent variables in an experiment. In a line graph, the an experiment. In a line graph, the manipulated manipulated (independent) variable(independent) variable is plotted on the _ is plotted on the _XX__ __ axis and the axis and the responding (dependent) variableresponding (dependent) variable is plotted on the _is plotted on the _YY__ axis.__ axis.

Where does distance go?Where does distance go?

Manipulated (Independent) Variable:

_______MIX___________________

Responding (Dependent) Variable: ________DRY__________________

E. Analysis and E. Analysis and ConclusionConclusion

After collecting data, a scientist After collecting data, a scientist must analyze the data and form must analyze the data and form conclusions based on the following conclusions based on the following questions:questions:

1. 1. Do the results _Do the results _supportsupport___ or ___ or __refuterefute__ the ___ the _hypothesishypothesis_?_?

Analysis and ConclusionAnalysis and Conclusion

2. 2. Is the experimental set-up _Is the experimental set-up _validvalid___?___? a. a. Was there a large enough _Was there a large enough _sample sample

sizesize___?___? b.b. Although no experimental set-up can be Although no experimental set-up can be

perfect, were the _perfect, were the _sources of errorsources of error_ _ minimized?minimized?

c. c. Was there only _Was there only _one variableone variable___ tested?___ tested?

3. 3. Is the experiment _Is the experiment _repeatablerepeatable__?__?

F. Constructing a TheoryF. Constructing a Theory

A A scientific theoryscientific theory is an is an explanation that has been _explanation that has been _testedtested__ __ many times by many different many times by many different __scientistsscientists_. _.

Although a theory has been Although a theory has been confirmed by repeated experiments, confirmed by repeated experiments, it may eventually be it may eventually be disprovendisproven..

IV. ENERGY FLOW IV. ENERGY FLOW (pp. 67-73)(pp. 67-73)

All living things require energy. The ultimate All living things require energy. The ultimate source of energy for the earth is the _source of energy for the earth is the _sunsun___. ___.

A. AutotrophsA. Autotrophs – “_ – “_Self-feederSelf-feeder____”. They ____”. They are also known as _are also known as _producersproducers__. Most __. Most producersproducers capture energy from the sun in a capture energy from the sun in a process called _process called _photosynthesisphotosynthesis_. _. Photosynthesis takes place in Photosynthesis takes place in the_the_chloroplastschloroplasts_ of plant cells. _ of plant cells.

The equation for The equation for photosynthesis photosynthesis is_is_CO2 + CO2 + H2O + light energy → C6H12O6 + O2H2O + light energy → C6H12O6 + O2___.___.

Photosynthesis

B. HeterotrophsB. Heterotrophs – Organisms that have to – Organisms that have to __obtain foodobtain food_ are called heterotroph or _ are called heterotroph or

__consumersconsumers____.____.

There are several categories of There are several categories of consumersconsumers:: 1. Herbivores 1. Herbivores – Eat _– Eat _plants (producers)plants (producers)____ 2. Carnivores 2. Carnivores – Eat _– Eat _animals (other consumers)animals (other consumers)____ 3. Omnivores3. Omnivores – Eat _ – Eat _plants & animalsplants & animals__________ 4. Detritivores 4. Detritivores – Obtain energy from _– Obtain energy from _deaddead bodies of bodies of

plants and animals; for example, _plants and animals; for example, _worms, worms, vultures, vultures, __ 5. Decomposers5. Decomposers – Break down _ – Break down _organicorganic__ __ matter. matter.

Most decomposers are in Kingdom _Most decomposers are in Kingdom _EubacteriaEubacteria or Kingdom or Kingdom __FungiFungi_._.

C. Energy in a Cell C. Energy in a Cell

C. Energy in a Cell C. Energy in a Cell – All organisms – All organisms (_(_producersproducers_and __and _consumersconsumers_) must _) must convert convert chemicalchemical__ energy present in __ energy present in __glucoseglucose_ and other food molecules into _ and other food molecules into usable energy. This conversion process is usable energy. This conversion process is known as _known as _metabolismmetabolism__ and the end-__ and the end-product is a re-chargeable “battery” used product is a re-chargeable “battery” used by all cells for energy known as _by all cells for energy known as _ATPATP___. ___. Most ATP is produced through the process Most ATP is produced through the process of _of _cellular respirationcellular respiration_. _.

The equation for The equation for cellular respirationcellular respiration is is __ C6H12O6 + O2 → CO2 + H2O +ATP C6H12O6 + O2 → CO2 + H2O +ATP__.__.

IV. ENERGY FLOW – A COMPARISON OF IV. ENERGY FLOW – A COMPARISON OF PHOTOSYNTHESIS & CELLULAR RESPIRATION PHOTOSYNTHESIS & CELLULAR RESPIRATION

(p. 232)(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 FlowC. Tracing Energy Flow

A. Trophic LevelsA. Trophic Levels - Each step in the pathway of - Each step in the pathway of energy flow is known as a __energy flow is known as a __trophic leveltrophic level_. The first _. The first trophic level is always a trophic level is always a ___producer___producer____. The 2nd ____. The 2nd trophic level is known as the primary (1 o) _consumer_ trophic level is known as the primary (1 o) _consumer_ and may be an _and may be an _herbivoreherbivore__ or __ or _omnivore_omnivore_. The last _. The last

step is always a _step is always a _decomposerdecomposer_._. 1. Food Chains 1. Food Chains – A food chain – A food chain

illustrates how energy is transferred by illustrates how energy is transferred by showing showing _feeding relationships between _feeding relationships between organismsorganisms. The arrows show the direction of . The arrows show the direction of _energy transfer – means “is eaten by”_._energy transfer – means “is eaten by”_.

Energy flows through an ecosystem in a series of steps in which

organisms transfer energy by being eaten

________________

_________________

= _________________http://fig.cox.miami.edu/Faculty/Dana/foodchain.jpg

PRODUCERS(Autotrophs)

CONSUMERS(Heterotrophs)

↑↑

FOOD CHAIN

Typical Food ChainTypical Food Chain

Energy (Sun)________ → __Producer____ → Energy (Sun)________ → __Producer____ → _1˚ Consumer (herbivore or omnivore)____ _1˚ Consumer (herbivore or omnivore)____ → →

__2˚ Consumer (carnivore or omnivore)____ → 2˚ Consumer (carnivore or omnivore)____ → _Decomposer_ _Decomposer_

EX:EX: Sun-> Grass->Grasshopper->Mouse->Snake-Sun-> Grass->Grasshopper->Mouse->Snake->Hawk>Hawk

··Which organism acts as a secondary consumer?Which organism acts as a secondary consumer?

··According to this food chain, which organism could be According to this food chain, which organism could be described as an herbivore?described as an herbivore?

··Which organism is the producer?Which organism is the producer?

··What are two terms that could be used to describe the What are two terms that could be used to describe the hawk?hawk?

Food WebsFood Webs

2. Food Webs – Typically feeding relationships are 2. Food Webs – Typically feeding relationships are more complex than illustrated in a food chain. more complex than illustrated in a food chain. Most organisms eat Most organisms eat _a variety of organisms _a variety of organisms and and _are eaten _are eaten by a variety of organisms. These by a variety of organisms. These interconnected pathways are more accurately interconnected pathways are more accurately shown in a food web.shown in a food web.

According to this food web . . . According to this food web . . . ··How many different producers are there?How many different producers are there? ··Is the grasshopper a producer, primary, or secondary consumer? Is the grasshopper a producer, primary, or secondary consumer? ··Is the grasshopper an herbivore, carnivore, or omnivore?Is the grasshopper an herbivore, carnivore, or omnivore? ··What organism(s) acts as the decomposer?What organism(s) acts as the decomposer? ··Give an example of an organism in this food web that acts as secondary and tertiary consumer.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 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.If the grass was destroyed, which organism would be most directly affected? Explain.

Ecological PyramidsEcological Pyramids

3. Ecological Pyramids – Although in theory, a 3. Ecological Pyramids – Although in theory, a food food _chain_ _chain_ or food or food _web_ _web_ can consist of can consist of unlimited numbers of unlimited numbers of _trophic levels_, _trophic levels_, in actuality in actuality this does not take place. On average, only this does not take place. On average, only 10%_ 10%_ of the energy stored in an organism is passed to of the energy stored in an organism is passed to the next trophic level. the next trophic level. _90% _90% of the energy is of the energy is either used by the organism to maintain either used by the organism to maintain _homeostasis__homeostasis_or lost as or lost as _heat__heat_to the environment. to the environment. Because of this, most food chains typically Because of this, most food chains typically consist of only consist of only _3 or 4 _3 or 4 trophic levels. Ecologists trophic levels. Ecologists use use _pyramids _pyramids to represent the amount of to represent the amount of _energy__energy_or or _matter__matter_at each at each _trophic level._trophic level.

V. NUTRIENTS IN AN V. NUTRIENTS IN AN ECOSYSTEM (pp. 74-80) ECOSYSTEM (pp. 74-80)

Unlike energy from the sun, nutrients are only Unlike energy from the sun, nutrients are only available to an ecosystem in specific available to an ecosystem in specific quantities and must be quantities and must be recycled_ recycled_ within and within and between ecosystems. Nutrients may become between ecosystems. Nutrients may become a _a _limiting factor limiting factor when they are depleted. when they are depleted.

Organisms require nutrients to _Organisms require nutrients to _build build biomolecules, cells, tissues, biomolecules, cells, tissues, etc. Although all etc. Although all nutrients, including _nutrients, including _water, water, are re-cycled, are re-cycled, there are a few nutrient cycles that are there are a few nutrient cycles that are especially important.especially important.

A. Water Cycle

B. Carbon CycleB. Carbon Cycle

Organisms require carbon to make Organisms require carbon to make _carbohydrates, _carbohydrates, _lipids_, _proteins_, and nucleic acids_lipids_, _proteins_, and nucleic acids. Carbon dioxide in . Carbon dioxide in the atmosphere is taken up by the atmosphere is taken up by _plants____ _plants____ and and _algae___ _algae___ for for _photosynthesis____. _photosynthesis____. (Algae are autotrophic, (Algae are autotrophic, unicellular organisms with cell walls made of cellulose and unicellular organisms with cell walls made of cellulose and chloroplasts that belong to kingdom _chloroplasts that belong to kingdom _Protista_). Protista_).

They produce glucose for They produce glucose for _cellular respiration___. _cellular respiration___. Humans Humans and other and other _consumers___ _consumers___ eat plants & algae, or they eat eat plants & algae, or they eat other organisms who have eaten plants & algae. The other organisms who have eaten plants & algae. The carbon from glucose is returned to the atmosphere as carbon from glucose is returned to the atmosphere as _CO _CO

22____, ____, a waste product of cellular respiration. In addition, a waste product of cellular respiration. In addition, erosion, burning of erosion, burning of _fossil fuels, _fossil fuels, andand _decomposition _decomposition recycle carbon.recycle carbon.

Carbon Cycle

4 main CARBON reservoirs in BIOSPHERE

CO2 inatmosphere

CO2 inOcean

BIOLOGY; Miller and Levine; Prentice Hall; 2006

1.In ____________ as CO2 gas 2.In _______ as dissolved CO2 gas3.On _______ in organisms, rocks, soil4.__________ as coal & petroleum (fossil

fuels) and calcium carbonate in rocks

atmosphereocean

landUnderground

1. Volcanic activity 2. Human activity (burning fossil

fuels) 3. Cellular respiration 4. Decomposition of dead

organisms

Where does CO2 in atmosphere come from?

C.C. Nitrogen CycleNitrogen Cycle

Nitrogen Cycle – Organisms require nitrogen to build _Nitrogen Cycle – Organisms require nitrogen to build _proteins proteins and nucleic acids.and nucleic acids.

The The _atmosphere__ _atmosphere__ is mostly nitrogen, but only is mostly nitrogen, but only _bacteria_ _bacteria_ produce the produce the _enzymes_ _enzymes_ needed to convert needed to convert nitrogen from the atmosphere to a useable form, a nitrogen from the atmosphere to a useable form, a process known as process known as _nitrogen fixation_nitrogen fixation. After nitrogen . After nitrogen fixation is carried out by bacteria in soil, the nitrogen fixation is carried out by bacteria in soil, the nitrogen compound in the soil is then absorbed by compound in the soil is then absorbed by _plants__ _plants__ and and used to make used to make _proteins & nucleic acids_. _proteins & nucleic acids_. When other When other organisms organisms _eat plants and algae_, _eat plants and algae_, they can re-use the they can re-use the nitrogen to build their own nitrogen to build their own proteins_ proteins_ andand _nucleic acids_. _nucleic acids_. When organisms dieWhen organisms die, _decomposers_ , _decomposers_ return the return the nitrogen to the soil where it may be taken up by nitrogen to the soil where it may be taken up by _plants _plants again or returned to the atmosphere by other again or returned to the atmosphere by other _bacteria_._bacteria_.

Nitrogen Cycle

Nitrogen Cycle

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:lightningVolcanic ActivitySpecialized bacteria

D. Phosphorus Cycle

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

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)

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

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

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

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

IV. ECOSYSTEM IV. ECOSYSTEM INTERACTIONS (pp. 90-INTERACTIONS (pp. 90-

93)93) Ecosystems are influenced by a combination Ecosystems are influenced by a combination

of of biologicalbiological and and physical factorsphysical factors. Together . Together biotic factors and abiotic factors determine biotic factors and abiotic factors determine the health of an ecosystem and its the health of an ecosystem and its _inhabitants_._inhabitants_.

The NicheThe Niche

A. The Niche - The role an organism plays in A. The Niche - The role an organism plays in its its _community _community is its is its _niche. _niche. An organism’s An organism’s niche is comprised of niche is comprised of _biotic__biotic_and and _abiotic__abiotic_factors, for example, the type of factors, for example, the type of food it eats, how it obtains its food, the way food it eats, how it obtains its food, the way it is food for other organisms, how & when it is food for other organisms, how & when it reproduces, its physical living it reproduces, its physical living requirements to survive, etc.requirements to survive, etc.

Warbler’s Niche

HABITAT vs NICHE?

Habitat is like an

organism’s ____________

Jellystone ParkNiche is like anorganism’s ______________

address

OCCUPATION

http://resmedicinae.sourceforge.net/logos/doctor.pnghttp://www.michcampgrounds.com/yogibears/yogi-picnic-cartoon.jpghttp://www.formaui.org/kamalii/critters.htm

http://www.electricwomen.com/hunterspoint/images/21-street-sign-moreell.jpg

B. Interactions Within a CommunityB. Interactions Within a Community

Community interactions have a powerful effect on an Community interactions have a powerful effect on an

ecosystem:ecosystem: 11. Competition – Competition occurs when . Competition – Competition occurs when

organisms are attempting to use the same organisms are attempting to use the same _resources _resources at the same time. Each different at the same time. Each different species within a community must have its own species within a community must have its own _niche_._niche_.

NO TWO SPECIES CAN SHARE THE SAME NICHE IN THE SAME HABITAT !

BIOLOGY; Miller and Levine; Prentice Hall; 2006

= ______________________________Competitive exclusion principle

PredationPredation

2. Predation – The organism that 2. Predation – The organism that does the killing and eating is the does the killing and eating is the _predator _predator and the food organism and the food organism is the is the _prey_._prey_.

3. Symbiosis – A relationship in which two 3. Symbiosis – A relationship in which two organisms organisms _live _live very closely together is very closely together is described as symbiosis.described as symbiosis.

There are three main types of symbiotic There are three main types of symbiotic relationships:relationships:

a. Mutualism – Both organisms a. Mutualism – Both organisms _benefit. _benefit. For For example, virtually all plant roots have mycorrhizae example, virtually all plant roots have mycorrhizae – a Fungus that resides within the plant roots. – a Fungus that resides within the plant roots. Fungus enhances absorption of Fungus enhances absorption of waterwater and and nutrientsnutrients

in roots; plant provides in roots; plant provides protectionprotection for the fungus. for the fungus.

CommensalismCommensalism

b. Commensalism – In commensalism, only one b. Commensalism – In commensalism, only one organism benefits, but the other organism _organism benefits, but the other organism _is is not harmednot harmed. .

For example, barnacles are small For example, barnacles are small _animals__animals_that that often attach themselves to whales. They do often attach themselves to whales. They do not harm the whales, and the barnacles benefit not harm the whales, and the barnacles benefit from the _from the _movement of water as whale swims movement of water as whale swims – – provides food for barnacles.provides food for barnacles.

Friendship

c. Parasitism – In parasitism, only c. Parasitism – In parasitism, only one organism benefits and the other one organism benefits and the other organism is organism is _harmed__ _harmed__ by the by the relationship. The organism that is relationship. The organism that is harmed is known as the harmed is known as the _host__. _host__. Examples of parasites include Examples of parasites include _tapeworms, hookworms, ticks, lice._tapeworms, hookworms, ticks, lice.

V. POPULATIONS WITHIN AN V. POPULATIONS WITHIN AN ECOSYSTEM (pp. 124-127)ECOSYSTEM (pp. 124-127)

Populations within an ecosystem cannot Populations within an ecosystem cannot have unlimited growth. There are have unlimited growth. There are conditions that have an impact on conditions that have an impact on population size known as _population size known as _limitinglimiting factors.factors. Limiting factors may described as Limiting factors may described as density-density-dependent dependent or density-independent.or density-independent.

A. Density-Dependent Limiting A. Density-Dependent Limiting FactorsFactors

A. Density-Dependent Limiting Factors – A. Density-Dependent Limiting Factors – Density-dependent factors depend on population Density-dependent factors depend on population

size; size; For example, For example, _competition___competition__ and availability of and availability of

_food___,_food___, _water__,_sunlight, shelter & mates. _water__,_sunlight, shelter & mates. Diseases andDiseases and crowding.crowding.

War, famine andWar, famine and disease for humansdisease for humans

B. Density-Independent Limiting B. Density-Independent Limiting FactorsFactors

B. Density-Independent Limiting Factors– These are B. Density-Independent Limiting Factors– These are factors that affect all populations the same way, factors that affect all populations the same way,

regardless of size. Examples include _regardless of size. Examples include _unusual unusual weatherweather, , natural disasters__,natural disasters__, and human activities and human activities such as _such as _cuttingcutting down trees, damming rivers, etc…down trees, damming rivers, etc…

If a nutrient is in _____________OR __________________it will LIMIT the growth of thepopulation= _____________LIMITING FACTOR

SHORT SUPPLY

CYCLES SLOWLY

http://www.wspa-international.org/exhibition/gallery/large_DeadKenyan%20droughtSPANA.jpg

During this drought, there was not enough food available and many kangaroosand cattle starved.

C. Climax CommunityC. Climax Community

C. Climax Community– A climax community C. Climax Community– A climax community is a is a _stable_stable community with very little community with very little population population

growth or decline. Each ecosystem has a growth or decline. Each ecosystem has a __carrying capacity_,carrying capacity_, a certain number of a certain number of organisms that can exist organisms that can exist _successfully_._successfully_. When the carrying capacity is exceeded, When the carrying capacity is exceeded, resources become a resources become a _limiting factor_,_limiting factor_, and and population numbers population numbers _decline_._decline_.