topic 6: ecology i. parts of an ecosystem ii. population dynamics

Topic 6: Topic 6: EcologyEcology

I. Parts of an EcosystemI. Parts of an EcosystemII. Population DynamicsII. Population Dynamics

Study of how organisms Study of how organisms INTERACTINTERACT with living and with living and

non-living thingsnon-living things

What is it?What is it?

What will we be looking at?What will we be looking at?

Parts of an ecosystemParts of an ecosystem Things that affect pop’n sizeThings that affect pop’n size Roles and relationships in an ecosystemRoles and relationships in an ecosystem Energy flow in an ecosystemEnergy flow in an ecosystem Importance of biodiversityImportance of biodiversity SuccessionSuccession Human impacts on the environmentHuman impacts on the environment

Ecosystem describes any portion of the

ENVIRONMENT

(ie. Decaying log, a pond, fish tank,

field of corn)

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The

environment

is every living and nonliving thing that surrounds an organism

Biotic FactorsBiotic Factors

ECOSYSTEM

Abiotic FactorsAbiotic Factors

ECOSYSTEMECOSYSTEM

What makes up an What makes up an ecosystem?ecosystem?

1. 1. BIOTIC FACTORSBIOTIC FACTORS• “Bio” means living• LIVING things in an

ecosystem• ie.PLANTS, ANIMALS, BACTERIA• Can you list the living

things that could live in this ecosystem?• Frogs, insects, fish, Frogs, insects, fish,

hawks, grasses, hawks, grasses, bacteria, amoeba bacteria, amoeba etc……..etc……..

2. ABIOTIC FACTORS2. ABIOTIC FACTORS• When you put “a” When you put “a”

in front of a word it in front of a word it negates itnegates it

• Means Means “NON-“NON-LIVINGLIVING” ” factorsfactors

• Can you list some Can you list some non-living factors non-living factors that affect the that affect the pond ecosystem?pond ecosystem?•WATER, LIGHT, WATER, LIGHT, TEMPTEMP, acidity, , acidity, oxygen and oxygen and nitrogen levelsnitrogen levels

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Ecological Levels of Ecological Levels of the Organization of the Organization of LifeLife

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Collectively all of the Collectively all of the Earth’s ecosystems Earth’s ecosystems make up the make up the

biospherebiosphere

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The specific environment in which

organisms live is their habitat

Ecosystem - populations in a community and the abiotic factors with which they interact (ex. Biomes)

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All the different populations are combined to form a

community

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All the organisms of a species that live in the same area, produce fertile offspring, and compete with each other for resources (food, mates, shelter, etc.) make up a

population

Organism - any unicellular or multicellular form exhibiting all of the characteristics of life, an individual.

•The lowest level of organization

Ecological Levels of the Ecological Levels of the Organization of LifeOrganization of Life• BIOSPHEREBIOSPHERE

• HABITAT (BIOME)HABITAT (BIOME)

• ECOSYSTEMECOSYSTEM

• COMMUNITYCOMMUNITY

• POPULATIONPOPULATION

• ORGANISMORGANISM

DecreasiDecreasing ng

amount amount of biotic of biotic

and and abiotic abiotic factorsfactors

What affects population sizes in an ecosystem?What affects population sizes in an ecosystem?• COMPETITION!COMPETITION!

• Struggle for Struggle for resources resources among among organismsorganisms

• If no competition, If no competition, populations would populations would grow grow INFINITELYINFINITELY (no (no limit!)limit!)

• Competition Competition maintains maintains FINITEFINITE (limited) pop’n sizes(limited) pop’n sizes• Finite populations Finite populations

limited by limited by LIMITING LIMITING FACTORSFACTORS• CAN BE ABIOTIC CAN BE ABIOTIC

OR BIOTICOR BIOTIC

Let’s look….Comparing Finite Let’s look….Comparing Finite and Infinite Populationsand Infinite Populations

INFINTITEINFINTITE GROWTHGROWTH

FINITE FINITE GROWTHGROWTH

What affects What affects population sizes in an population sizes in an

ecosystem?ecosystem?A) ABIOTIC LIMITING FACTORSA) ABIOTIC LIMITING FACTORS

Amount and intensity of Amount and intensity of SUNLIGHTSUNLIGHT Amount of Amount of WATERWATER Amount of dissolvedAmount of dissolved OXYGEN OXYGEN

(lakes, rivers, etc)(lakes, rivers, etc) Acid levelAcid level TEMPERATURETEMPERATURE rangerange MINERALSMINERALS available available

What affects population sizes in an What affects population sizes in an ecosystemecosystem??

B) BIOTIC LIMITING FACTORS•PREDATOR/PREYPREDATOR/PREY relationships

• Predators limit prey population sizes by eating them

• Prey limit predator population sizes by dying/being killed • If too many killed, predators starve• Adapting (survival of the best

adapted)

Let’s take a look…. Effects of Predator/Prey RelationshipLet’s take a look…. Effects of Predator/Prey Relationship

As you can see, AS PREY POPULATION AS PREY POPULATION DECREASES, THE PREDATOR’S POPULATION DECREASES, THE PREDATOR’S POPULATION DECREASES (DECREASES (Direct relationshipDirect relationship))

What do we call it when a species reaches its What do we call it when a species reaches its limit?limit?

• EVERY population in an ecosystem has a EVERY population in an ecosystem has a CARRYING CARRYING CAPACITY (K)CAPACITY (K)

• THE # OF ORGANISMS OF A SINGLE SPECIES AN THE # OF ORGANISMS OF A SINGLE SPECIES AN ECOSYSTEM CAN SUPPORTECOSYSTEM CAN SUPPORT• Determined by Determined by BIOTICBIOTIC and and ABIOTICABIOTIC factorsfactors

• EX:EX: a fox population is affected by how much it a fox population is affected by how much it has to eat (biotic) and also temperature has to eat (biotic) and also temperature (abiotic)(abiotic)

• Once K is reached, population will remain Once K is reached, population will remain stable stable unless major changes in biotic and abiotic factorsunless major changes in biotic and abiotic factors

Carrying Capacity (K) of a Stable Carrying Capacity (K) of a Stable PopulationPopulation

Part 2: POPULATION INTERACTIONS

How organisms interact in an ecosystem!

What role are you up for?

Competitive Exclusion PrincipleCompetitive Exclusion Principle

• If two different species compete for the same food source or reproductive sites, one species may be eliminated.

• This establishes one species per niche in a community.

A. What does it mean to have a role in an ecosystem?

NICHE:NICHE:• THETHE ROLEROLE (NOT SPACE!!!!!)(NOT SPACE!!!!!) AN AN

ORGANISM PLAYS IN ITS ECOSYSTEMORGANISM PLAYS IN ITS ECOSYSTEM• ONLY ONLY ONEONE SPECIES CAN SPECIES CAN OCCUPY OCCUPY A A

NICHENICHE AT A TIMEAT A TIME• LEADS TO LEADS TO COMPETITIONCOMPETITION IF MORE THAN IF MORE THAN

ONE SPECIES WANTS ROLEONE SPECIES WANTS ROLE• SIMILARSIMILAR SPECIES CAN SPECIES CAN COEXIST COEXIST AS AS

LONG AS THEY HAVE DIFFERENT LONG AS THEY HAVE DIFFERENT NICHES!NICHES!• EX:EX: p102 in RB – WARBLERS p102 in RB – WARBLERS

HOW CAN I REMEMBER THAT HOW CAN I REMEMBER THAT “NICHE” MEANS ROLE AND “NICHE” MEANS ROLE AND NOTNOT SPACE?SPACE?

• THINK OF A PLAY!• EVERY ROLE NEEDS

TO BE FILLED IN ORDER FOR THE PLAY TO WORK!

• IF MORE THAN TWO FOLKS (SPECIES) WANT A ROLE, THERE IS COMPETITION AND THE BEST WINS!

Food chainFood chain Food webFood web(1 path of energy)(1 path of energy) (all possible energy paths) (all possible energy paths)

What are the relationships in an ecosystem?

B. What are the relationships in an B. What are the relationships in an ecosystem?ecosystem?1. FOOD CHAINS 1. FOOD CHAINS • IllustrateIllustrate NUTRITIONAL RELATIONSHIPS NUTRITIONAL RELATIONSHIPS

between predators and preybetween predators and prey• 1 path of energy1 path of energy• Specific organisms are includedSpecific organisms are included• Let’s take a look!Let’s take a look!

FOOD CHAINSFOOD CHAINS

Feeding Relationships

A. Autotrophs (Producers):

Make own food (grass)B. Heterotrophs (Consumers):

•Herbivores: Eat plants (grasshopper)•Carnivores: Eat animals (snake)•Omnivores: Eat plants and animals (humans)•Scavengers: Eat dead things; life’s clean-up crew! (vultures)•Decomposers: life’s recyclers (bacteria and fungi))

2. SYMBIOTIC RELATIONSHIPS• When organisms live in REALLY close quarters

1. Parasitism: Live off other orgs but don’t kill them (some worms, ticks, fleas)

2. Mutualism: Orgs that both benefit (Clownfish and sea anemone)

3. Commensalism: One org benefits the other - neither harmed or benefitted (Whale and barnacles)

PARASITISM MUTALISM COMMENSALISM

3. FOOD WEBS:•All food chains in an ecosystem are illustrated in a food web•INVOLVES all possible energy paths

Food Webs Food Webs are diagrams that show more are diagrams that show more complex feeding relationshipscomplex feeding relationships

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A simplified food web at a pond

Let’s talk energy! The fuel of life!

• Ask yourself: Where does our ultimate source of energy come from?• The SUN of course!

• Ask yourself: Which orgs can harness sun’s energy and make food?• PLANTS of course!

• Ask yourself: What happens to the plant’s energy when a herbivore eats it?

• • Ask yourself: What happens to the herbivore’s

energy when a carnivore eats it?

• Ask yourself: What happens to the carnivore’s energy when another carnivore eats it?

Decreases

Decreases

Decreases

Every organism uses ENERGY to carry out LIFE processes

If an organism is eaten, it will give less energy to the predatorTHEREFORE, ENERGY DECREASES AS YOU MOVE UP A FOOD CHAIN!

1. What happens to ENERGY in an ecosystem?

Herbivores - Herbivores - CATERPILLARCATERPILLAR

Carnivores - Carnivores - BIRDBIRD

Producers(AutotropProducers(Autotrophs) – OAK TREEhs) – OAK TREE

•WE USE AN ENERGY PYRAMID TO SHOW THIS

•see fig 6-7 and 6-8 on page 107 in your review book!

• As energy is transferred, much of it is lost to the environment

Let’s watch : Let’s watch : http://www.brainpop.com/science/energy/energypyramid

D. RECYCLING NUTRIENTS• DECOMPOSERS extract what little nutrients are left• They return raw materials (nitrogen) back to soil• Other orgs continually recycling CARBON DIOXIDE,

OXYGEN, AND NITROGEN• ENERGY IS NEVER RECYCLED!• involves the processes of RESPIRATION and

PHOTOSYNTHESIS.

Let’s look at pg 108 in RB RECYCLING OF MATERIALS IN ECOSYSTEMS

• Let’s Watch: brain pop carbon CYCLE VIDEO (2:32)