1 Chapter 2 Principles of Ecology 2.1 Organisms and Their Relationships

Chapter 2 Principles of Chapter 2 Principles of EcologyEcology

2.1 Organisms and Their 2.1 Organisms and Their RelationshipsRelationships

What is ecology?What is ecology?

OikosOikos Greek for “homestead” Greek for “homestead”OlogyOlogy means “study of” means “study of” Scientific study of interactions Scientific study of interactions

among organisms and their among organisms and their environmentenvironment

Reveals relationships among living Reveals relationships among living things (biotic) and nonliving (abiotic) things (biotic) and nonliving (abiotic) parts of the worldparts of the world

What is ecology?What is ecology?

Uses both quantitative and descriptive Uses both quantitative and descriptive researchresearch

Combines information and techniques Combines information and techniques from many scientific fields:from many scientific fields:– MathematicsMathematics– ChemistryChemistry– PhysicsPhysics– GeologyGeology– And many othersAnd many others

Aspects of Ecological StudyAspects of Ecological Study Biosphere: portion of Biosphere: portion of

the Earth that the Earth that supports lifesupports life– High in atmosphere to High in atmosphere to

bottom of oceanbottom of ocean– Extends several Extends several

kilometers above the kilometers above the Earth’s surface and Earth’s surface and several kilometers several kilometers below the surface of the below the surface of the ocean ocean

– Comparable to peel of Comparable to peel of an applean apple

– Very diverse climateVery diverse climate

Living thing affected by:Living thing affected by:

Abiotic factorsAbiotic factors– Air currentsAir currents– TemperatureTemperature– MoistureMoisture– LightLight– Soil compositionSoil composition– TerrainTerrain– And many othersAnd many others

Living thing affected by:Living thing affected by:

Biotic factorsBiotic factors– Same species for Same species for

protection, protection, competition, food, competition, food, and reproductionand reproduction

– Other species for Other species for all but reproductionall but reproduction

Tree decay

Levels of Organization in EcologyLevels of Organization in Ecology

Need to study Need to study more than just an more than just an individual to get individual to get the whole storythe whole story

Need to study Need to study relationships or relationships or interactions among interactions among organisms of the organisms of the same and different same and different speciesspecies

Levels of Organization in EcologyLevels of Organization in Ecology

◊◊BiosphereBiosphere– BiomeBiome

EcosystemEcosystem– CommunityCommunity

PopulationPopulation

- Organism- Organism

PopulationsPopulations

A group of A group of organisms of one organisms of one species that species that interbreed and live interbreed and live together in the together in the same place at the same place at the same timesame time

Compete with each other for food, Compete with each other for food, water, space, light and other water, space, light and other resources in short supplyresources in short supply

How organisms share resources How organisms share resources determines how far apart they live determines how far apart they live and how large a population getsand how large a population gets

Some species Some species reduce competition reduce competition by larvae and adult by larvae and adult stages living in stages living in different different environments and environments and using different using different resources as food resources as food (frogs and many (frogs and many insects)insects)

Individuals Interact within Individuals Interact within CommunitiesCommunities

Community: collection of interacting Community: collection of interacting populations (all the populations at populations (all the populations at one place and time)one place and time)

Change in one population will cause Change in one population will cause change in another populationchange in another population– Small changesSmall changes– Large changesLarge changes

Interactions among living things Interactions among living things and abiotic factors and abiotic factors

Ecosystem: interaction of populations Ecosystem: interaction of populations in a community and nonliving in a community and nonliving (physical) surroundings(physical) surroundings

Three kinds of ecosystemsThree kinds of ecosystems– Terrestrial (land)Terrestrial (land)– Fresh waterFresh water– Marine: 75% of the earthMarine: 75% of the earth

Organisms in EcosystemsOrganisms in Ecosystems

Habitat: place where an organism lives its Habitat: place where an organism lives its life (home)life (home)

Niche: the role and position a species Niche: the role and position a species plays in its environmentplays in its environment– All the interactions with abiotic and All the interactions with abiotic and

biotic factorsbiotic factors– Everything the species doesEverything the species does– How it uses resourcesHow it uses resources– Its jobIts job

Even though two species occupy the Even though two species occupy the same habitat, they do not occupy the same habitat, they do not occupy the same niche because resources (food, same niche because resources (food, shelter) are used in different waysshelter) are used in different ways

It is an advantage for a species to It is an advantage for a species to occupy a different niche, unique occupy a different niche, unique strategies are important to reduce strategies are important to reduce competitioncompetition

SymbiosisSymbiosis

Permanent, close association Permanent, close association between two or more organisms of between two or more organisms of different speciesdifferent species

Three types of symbiosisThree types of symbiosis– CommensalismCommensalism– MutualismMutualism– ParasitismParasitism

CommensalismCommensalism

One species benefits, other species One species benefits, other species not harmed or benefitednot harmed or benefited

Few examples because further study Few examples because further study usually reveals mutualism or usually reveals mutualism or parasitismparasitism

Cattle egrets follow Cattle egrets follow cattle to feed on cattle to feed on the insects stirred the insects stirred up by the grazing up by the grazing cattle. cattle.

Egret benefits as it Egret benefits as it gets more foodgets more food

Cattle is neither Cattle is neither helped nor harmedhelped nor harmed

Orchids growing on Orchids growing on trees have a home trees have a home and moistureand moisture

Orchids benefit Orchids benefit while the tree is while the tree is not affectednot affected

MutualismMutualism

Both species benefitBoth species benefit

MutualismMutualism

A remarkable 3-way A remarkable 3-way mutualism appears to mutualism appears to have evolved between have evolved between

an ant, a butterfly an ant, a butterfly caterpillar, and an acacia caterpillar, and an acacia

in the American in the American southwest. The southwest. The

caterpillars have nectar caterpillars have nectar organs which the ants organs which the ants

drink from, and the drink from, and the acacia tolerates the acacia tolerates the

feeding caterpillars. The feeding caterpillars. The ants appear to provide ants appear to provide

some protection for both some protection for both plant and caterpillar.plant and caterpillar.

Research of Diane Wagner, American Museum of Natural History Southwestern Research Station

MutualismMutualism

Ants “tending” soybean aphidsAnts “tending” soybean aphids

ParasitismParasitism

One organism One organism benefits the other benefits the other is harmed but is harmed but usually not killedusually not killed

Ring Worm

2.2 Flow of Energy in an 2.2 Flow of Energy in an EcosystemEcosystem

How Organisms Obtain EnergyHow Organisms Obtain Energy

Ultimate source of energy is the sunUltimate source of energy is the sun Producers use the sun’s energy to Producers use the sun’s energy to

make foodmake food Consumers eat producers and other Consumers eat producers and other

consumersconsumers

Autotrophs: “auto” = self; “troph”= Autotrophs: “auto” = self; “troph”= energyenergy– Most are photoautotrophs: organisms Most are photoautotrophs: organisms

that use the sun’s energy to make food that use the sun’s energy to make food in the process of photosynthesis; all in the process of photosynthesis; all have chlorophyllhave chlorophyll

– Some are chemoautotrophs; make food Some are chemoautotrophs; make food by using energy stored in chemical by using energy stored in chemical bonds (some Archaebacteria)bonds (some Archaebacteria)

PhotoautotrophsPhotoautotrophsCyanobacteria

Plants

Heterotrophs: “hetero”= other; Heterotrophs: “hetero”= other; “troph”= energy“troph”= energy– Can’t make food so must feed on other Can’t make food so must feed on other

organismsorganisms– Herbivores: only eat autotrophsHerbivores: only eat autotrophs– Carnivores: only eat other heterotrophsCarnivores: only eat other heterotrophs– Omnivore: eat both autotrophs and Omnivore: eat both autotrophs and

heterotrophsheterotrophs

Heterotrophs: “hetero”= other; Heterotrophs: “hetero”= other; “troph”= energy, cont.“troph”= energy, cont.– Scavengers: feed on dead (carrion and Scavengers: feed on dead (carrion and

refuse)refuse)– Decomposers: breakdown and absorb Decomposers: breakdown and absorb

nutrients from dead organisms (fungi, nutrients from dead organisms (fungi, protozoans, many bacteria)protozoans, many bacteria)

HeterotrophsHeterotrophsCarnivoreCarnivore

HerbivoreHerbivore

DecomposerDecomposer

ScavengerScavenger

DetritivoresDetritivores– Eat fragments of Eat fragments of

dead matter in an dead matter in an ecosystem, and ecosystem, and return nutrients to return nutrients to the soil, air, and the soil, air, and water where the water where the nutrients can be nutrients can be reused by reused by organisms.organisms.

– Also considered Also considered heterotrophsheterotrophs

Matter and Energy FlowMatter and Energy Flow

Food Chains: simple model to show energy Food Chains: simple model to show energy flow in an ecosystem; one possible routeflow in an ecosystem; one possible route

Food web: several interconnected food Food web: several interconnected food chainschains– shows that an organism occupies more than shows that an organism occupies more than

one trophic levelone trophic level– Expresses more possible feeding relationships Expresses more possible feeding relationships

at each trophic levelat each trophic level– More realistic than a food chainMore realistic than a food chain

Food ChainFood Chain

Arrows indicate direction energy Arrows indicate direction energy flowsflows

Usually 3 to 5 trophic (energy) levelsUsually 3 to 5 trophic (energy) levels On average only 10% of energy is On average only 10% of energy is

transferred to next trophic leveltransferred to next trophic level– Most energy is lost as heatMost energy is lost as heat– Also lost as urine, feces and otherAlso lost as urine, feces and other

Food ChainFood Chain

Top CarnivoreTop Carnivore

CarnivoreCarnivore

OmnivoreOmnivore

HerbivoreHerbivore

ProducerProducer

Food WebFood Web

Trophic level is one step in a food Trophic level is one step in a food chainchain

Organisms can occupy more than Organisms can occupy more than one trophic levelone trophic level

Important part of organism’s niche is Important part of organism’s niche is how it obtains energyhow it obtains energy

Energy and Trophic LevelsEnergy and Trophic Levels

Energy PyramidEnergy Pyramid

Energy PyramidsEnergy Pyramids

Pyramid of NumbersPyramid of Numbers– Count the number of Count the number of

organisms at each organisms at each levellevel

– Numbers decrease as Numbers decrease as move up the pyramidmove up the pyramid

– Not always reveals Not always reveals true relationship as true relationship as one tree (producer) one tree (producer) could support 50,000 could support 50,000 insects (herbivore)insects (herbivore)

Pyramid of BiomassPyramid of Biomass– Use dry weight of Use dry weight of

organisms at each organisms at each levellevel

Pyramid of NumbersPyramid of Numbers Pyramid of BiomassPyramid of Biomass

2.3 Cycling of Matter2.3 Cycling of Matter

Cycles in NatureCycles in Nature

Energy flows, nutrients cycleEnergy flows, nutrients cycle Atoms of carbon, nitrogen and other Atoms of carbon, nitrogen and other

elements in your body today made up the elements in your body today made up the bodies of other organismsbodies of other organisms

Matter including nutrients are constantly Matter including nutrients are constantly recycledrecycled

The cycling of nutrients in the biosphere The cycling of nutrients in the biosphere involves both matter in living organisms involves both matter in living organisms and physical processes found in the and physical processes found in the environment such as weathering.environment such as weathering.

Nitrogen CycleNitrogen Cycle

Phosphorus CyclePhosphorus Cycle

1 Chapter 2 Principles of Ecology 2.1 Organisms and Their Relationships

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