Chapter 3

Introduction to Ecological PrinciplesSeptember October 20111study of how organisms interact with one another and with their non-living environment.from Greek oikos meaning housesegment of biological sciences focused on organism to biosphere interactionsThe Field of Ecology

2Ecology is the study of organisms in their HomeOikos = HomeBy ecology we mean the body of knowledge concerning the economy of nature--the investigation of the total relations of the animal both to its inorganic and its organic environment; including, above all, its friendly and inimical relations with those animals and plants with which it comes directly or indirectly into contact--in a word, ecology is the study of all those complex interrelations referred to by Darwin as the conditions of the struggle for existence.Ernst Haeckel, 18703Unit 2 Summary Ch.3-7Topic: Ecology & EvolutionBasics of Ecology Atmospheric StructureClimate & WeatherBiomes & Aquatic Life ZonesBiogeochemical cyclingProductivitySpecies diversityEvolutionInter- and intraspecific relationshipsEcological succession

Fig. 3-6, p. 54Lithosphere (crust, top of upper mantle) RockSoilVegetation and animals AtmosphereOceanicCrustContinental CrustLithosphereUpper mantleAsthenosphereLower mantleMantleCoreBiosphereCrustCrust (soil and rock)Biosphere (living and dead organisms) Hydrosphere (water) Atmosphere (air)5Figure 3.6Natural capital: general structure of the earth.

The Sun: The Ultimate SourceSolar energy flows through the biosphere.warms the atmosphereevaporates and recycles watergenerates winds supports the growth of producersFigure 3-86

What Sustains Life on Earth?Solar energyFigure 3-7GravityCycling of matter7

Biomes & Aquatic Life ZonesFigure 3-98Energy FlowFirst Law of Thermodynamics: Energy cannot be created nor destroyed, but can change from one form to another.Second Law of Thermodynamics: When energy is converted to another form, some of it is changed to heat that is unavailable to do further work.For thermodynamic purposes, matter can be thought of as a form of energy.Energy flows through communities (usually from the sun), losing usable energy each time one organism consumes another.9

Fig. 3-10, p. 57SunOxygen (O2)Carbon dioxide (CO2)Secondary consumer(fox)Soil decomposersPrimaryconsumer(rabbit)PrecipitationFalling leaves and twigsProducerProducersSoluble mineral nutrientsWater10Figure 3.10Natural capital: major components of an ecosystem in a field.PopulationsA population is a group of interacting organisms of the same species occupying a specific area at the same time.Why study the population?management unitsource of natural resources/natural capital

Figure 3-4: Population of monarch butterflies on a milkweed plant

Organisms may appear to be alike and be different species. For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.

11Characteristics of PopulationsHabitat place where a population normally lives

Range area over which we can find speciesMay be a specific habitat or a collection of suitable habitatsSometimes called distributionCredit: Charissa Morris / USFWS Credit: U.S. Fish & Wildlife Service Organisms may appear to be alike and be different species. For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.

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Fig. 3-11, p. 58Zone of intoleranceOptimum rangeZone of physiological stressZone of physiological stressZone of intoleranceTemperatureLowHighNoorganismsFeworganismsUpper limit of tolerancePopulation sizeAbundance of organismsFew organismsNoorganismsLower limit of toleranceFactors That Limit Population Growth13Figure 3.11Natural capital: range of tolerance for a population of organisms, such as fish, to an abiotic environmental factorin this case, temperature. These restrictions keep particular species from taking over an ecosystem by keeping their population size in check.

Factors That Limit Population GrowthThe physical conditions of the environment can limit the distribution of a species.Figure 3-1214Types of Organisms in EcosystemsAutotrophic organisms = ProducersMeans self feedersA. Photosynthetic organismsUse light as an energy sourceGreen plants, algae, photosynthetic bacteria

B. Chemosynthetic bacteriaOxidize inorganic chemicals as an energy sourceUse reduced forms of sulfur, nitrogen, ironThiobacillus thiooxidans, Nitrobacter spp., Nitrosomonas spp., Thiobacillus ferroxidans

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Photosynthesis: A Closer LookChlorophyll molecules in the chloroplasts of plant cells absorb solar energy.This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen.Figure 3-A16Types of Organisms in Ecosystems (continued)Heterotrophic organismsMeans to feed on othersA. ConsumersAnimals which usually eat other living thingsHerbivores consume producers Carnivores consume other consumersOmnivores consume both producers and consumersB. Detritivores & DecomposersWorms, maggots, small arthropods that are shredders of large detritusBacteria & fungi17

What are these?18Type of Organism?

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Decomposers and DetrivoresDecomposers: Recycle nutrients in ecosystems.Detrivores: Insects or other scavengers that feed on wastes or dead bodies.Figure 3-1320

Detritus21

Leaf Litter Detritus22Dung Beetle (Detritivore)

23DecomposersBacteria

Fungi

24Aerobic and Anaerobic Respiration: Getting Energy for SurvivalOrganisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need.This is usually done through aerobic respiration.The opposite of photosynthesis

25Aerobic and Anaerobic Respiration: Getting Energy for SurvivalAnaerobic respiration or fermentation:Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen.The end products vary based on the chemical reaction:Methane gasEthyl alcoholAcetic acidHydrogen sulfide26

Two Secrets of Survival: Energy Flow and Matter RecycleAn ecosystem survives by a combination of energy flow and matter recycling.Figure 3-1427

ENERGY FLOW IN ECOSYSTEMSFood chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem.Figure 3-1728Food Chains

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Food WebsTrophic levels are interconnected within a more complicated food web.Figure 3-1830Energy Flow in an Ecosystem: Losing Energy in Food Chains and WebsIn accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.

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Trophic Levels & Energy Pyramids32

Fig. 3-19, p. 66HeatHeatHeatHeatHeatDecomposersTertiaryconsumers(human)Producers(phytoplankton)Secondaryconsumers(perch)Primaryconsumers(zooplankton)101001,00010,000Usable energyAvailable atEach tropic level(in kilocalories)33Figure 3.19Natural capital: generalized pyramid of energy flow showing the decrease in usable energy available at each succeeding trophic level in a food chain or web. In nature, ecological efficiency varies from 2% to 40%, with 10% efficiency being common. This model assumes a 10% ecological efficiency (90% loss in usable energy to the environment, in the form of low-quality heat) with each transfer from one trophic level to another. QUESTION: Why is it a scientific error to call this a pyramid of energy?Ecological Pyramids ExplainedProductivityDefined as the rate at which organisms in one trophic level convert energy from the previous trophic level into its own levelPrimary ProductivityThe rate at which producers either photosynthesize (green plants) or oxidize inorganic compounds (chemosynthetic bacteria)Secondary ProductivityThe rate at which consumers or decomposers convert energy from a prior trophic level into their own level35Primary ProductivityGross Primary Productivity (GPP or Pg)The total productivity of all producers in an ecosystem (e.g. total amount of energy fixed by photosynthesis and/or chemosynthesis)Rate at which an ecosystems producers convert solar energy into chemical energy as biomass.Respiration (R)Metabolic costs of the producersNet Primary Productivity (NPP or Pn)The amount of productivity left over after producer metabolism is subtracted This equals the amount of energy remaining for producer growth and reproductionNPP = Growth + ReproductionGPP = NPP + R

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GPP=NPP+RNPP = Growth + ReproductionGPP = Total Assimilation of organic material37

Fig. 3-20, p. 66Gross primary productivity(grams of carbon per square meter)38Figure 3.20Natural capital: gross primary productivity across the continental United States based on remote satellite data. The differences roughly correlate with variations in moisture and soil types. (NASAs Earth Observatory)

Net Primary Production (NPP)NPP = GPP RRate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R).Figure 3-2139Measuring Primary ProductionHarvest MethodTraditionally used in terrestrial communitiesLight/Dark Bottle MethodUsed in aquatic communitiesRadioisotope MethodsCan be used in either terrestrial or aquatic communities

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Comparison of Net Primary Productions41

What are natures three most productive and three least productive systems?Figure 3-2242