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Chapter 3

The Principles of The Principles of EcologyEcology

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I- The Beginning of EcologyNatural history lead to ecologyNatural history lead to ecology

• Science that studies the interaction Science that studies the interaction between organisms and their between organisms and their environmentenvironment

• Combines knowledge between many Combines knowledge between many sciences: Biology, chemistry, physic and sciences: Biology, chemistry, physic and earth scienceearth science

3I- B. The living Environment: Biotic factors

• All living things are found in a layer All living things are found in a layer called the called the BiosphereBiosphere

• Biosphere is made up of different Biosphere is made up of different environments : Aquatic / Terrestrialenvironments : Aquatic / Terrestrial

• Environment consist of Environment consist of

–Nonliving factors ( Nonliving factors ( Abiotic factorsAbiotic factors))

–Living factors ( Living factors ( Biotic factorsBiotic factors))

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I- C. Abiotic Factors

• AbioticAbiotic factorsfactors can have obvious can have obvious effects on living things and often it effects on living things and often it determines which species can determines which species can survive.survive.

• Example: Grasslands only support Example: Grasslands only support small plants and many grassing small plants and many grassing animalsanimals

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II- Levels of Organization

• All organisms depend on others for food, All organisms depend on others for food, shelter, reproduction or protection.shelter, reproduction or protection.

• Ecologist study interaction among Ecologist study interaction among organisms at several different levels.organisms at several different levels.

• Levels of organization provide a tool to Levels of organization provide a tool to use in planning their research.use in planning their research.

–Example: Studying bees Vs. foxesExample: Studying bees Vs. foxes

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• IndividualIndividual

• PopulationsPopulations

• CommunitiesCommunities

• EcosystemEcosystem

• BiospheresBiospheres

Levels of organization. Page 59

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II- A. Interaction within Populations

KINDS OF COMPETITIONS:KINDS OF COMPETITIONS:

• among individuals in a population among individuals in a population

• between populations in a communitybetween populations in a community

• between communities in an Ecosystembetween communities in an Ecosystem

HOW TO AVOID COMPETIONHOW TO AVOID COMPETION

• Alternating generationAlternating generation

• MetamorphosisMetamorphosis

8ALTERNATING GENERATION

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METAMORPHOSIS

10II- B. Individuals interact in Communities

• No population or organisms lives No population or organisms lives independently of other species.independently of other species.

• Community is a collections of Community is a collections of interacting populationsinteracting populations

• Change in one population causes change Change in one population causes change in anotherin another

–Example: more people less vegetationExample: more people less vegetation

11II- C. Interaction between Abiotic and Biotic factors

• Ecosystems are interaction among the Ecosystems are interaction among the populations in a community and their populations in a community and their physical surroundings.physical surroundings.

• Kinds of ecosystems:Kinds of ecosystems:

–TerrestrialTerrestrial

–Aquatic ( 75% of earth’s surface)Aquatic ( 75% of earth’s surface)

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II- D. Where and how organisms live

• Every organism plays a role in their Every organism plays a role in their communitycommunity

• All help maintain a balance All help maintain a balance ((HomeostasisHomeostasis))

• Role played is the organism’s Role played is the organism’s NICHENICHE

• HabitatHabitat is place where organism lives is place where organism lives

–many species usually share habitatsmany species usually share habitats

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III- How organisms Interact

Feeding relationships: How organisms Feeding relationships: How organisms obtain energyobtain energy

• AutotrophsAutotrophs = capture and store light = capture and store light energyenergy

• HeterotrophsHeterotrophs = depend on autotrophs for = depend on autotrophs for a food sourcea food source

• CarnivoresCarnivores = organism that depends on = organism that depends on other heterotrophs as a food sourceother heterotrophs as a food source

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III- How organisms Interact part 2

• ScavengersScavengers = depend on dead organisms = depend on dead organisms as food sourceas food source

• OmnivoresOmnivores = eat a variety of food both = eat a variety of food both plants and animalsplants and animals

• DecomposersDecomposers = break down and absorb = break down and absorb nutrients from dead organismsnutrients from dead organisms

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III- B. Close relationship for survival

• Symbiosis Symbiosis : close and permanet : close and permanet association between organisms of association between organisms of different species.different species.

• CommensalismCommensalism: one species is benefited : one species is benefited and the other is neither helped or harmedand the other is neither helped or harmed

• MutualismMutualism: both species benefit : both species benefit

• parasitismparasitism: one benefits at the expense of : one benefits at the expense of the otherthe other

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III- B. Close relationship for survival

• more Symbiotic relationshipsmore Symbiotic relationships

–parasitismparasitism: one benefits at the expense : one benefits at the expense of the otherof the other

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IV- A. Matter & Enery in Ecosystem

• Food ChainFood Chain

– each link provides less energy then the each link provides less energy then the previous. (energy loss by heat and motion)previous. (energy loss by heat and motion)

– 3links in a food chain good / 5 are bad3links in a food chain good / 5 are bad

– each level or link is called a each level or link is called a Trophic levelTrophic level

– many food chains cross and interconnect many food chains cross and interconnect this is called a (this is called a (Food WebFood Web))

18Food Web

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Pyramid numbers

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Energy Pyramid

21IV- C. Cycling maintains Homeostasis

• Water cycleWater cycle

• Carbon dioxide cycleCarbon dioxide cycle

• Nitrogen cycleNitrogen cycle

• Phosphorus cyclePhosphorus cycle

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Water cycle

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Carbon Dioxide cycle

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Nitrogen cycle