Principles of Principles of EcologyEcology

What is Ecology?What is Ecology?

• Branch of biology developed from Branch of biology developed from natural historynatural history

• Scientific study of interactions among Scientific study of interactions among organisms and their environmentsorganisms and their environments

• Reveals relationships among living Reveals relationships among living and nonliving parts of the world.and nonliving parts of the world.

• Ecologists use research informationEcologists use research information

How Organisms Obtain energyHow Organisms Obtain energy

• The ultimate source of energy is the The ultimate source of energy is the sunsun

The producers: AutotrophsThe producers: Autotrophs

• Plants use the sun’s energy to make Plants use the sun’s energy to make food (photosynthesis)food (photosynthesis)

• Autotrophs: Organisms that use Autotrophs: Organisms that use energy from the sun or energy in energy from the sun or energy in chemical compounds to make their chemical compounds to make their own nutrientsown nutrients

• Plants are the most common Plants are the most common autotrophsautotrophs

The consumers: HeterotrophsThe consumers: Heterotrophs• Heterotrophs: Organisms that cannot make Heterotrophs: Organisms that cannot make

their own foodtheir own food

• Types of heterotrophs: Herbivores, Types of heterotrophs: Herbivores, Omnivores, CarnivoresOmnivores, Carnivores

• Herbivores: Organisms which eat only plantsHerbivores: Organisms which eat only plants

• Omnivores: Organisms which eat both plants Omnivores: Organisms which eat both plants and animalsand animals

• Carnivores: Organisms which eat animalsCarnivores: Organisms which eat animals

• Decomposers: Organisms which break down Decomposers: Organisms which break down and absorb nutrients from dead organismsand absorb nutrients from dead organisms

Matter and energy flow in Matter and energy flow in ecosystemsecosystems

• Ecologists study the flow of energy Ecologists study the flow of energy through ecosystemsthrough ecosystems

Food Chains: Pathways for Food Chains: Pathways for matter and energymatter and energy

• Food Chain: A simple model that Food Chain: A simple model that scientists use to show how matter scientists use to show how matter and energy move through an and energy move through an ecosystemecosystem

• Food chains consist of at least 3 Food chains consist of at least 3 steps and usually no more than 5steps and usually no more than 5

• By the end of the chain a lot of the By the end of the chain a lot of the energy is lostenergy is lost

• Energy loss occurs through heat loss Energy loss occurs through heat loss in each organismin each organism

Food Chain RelationshipFood Chain Relationship

Trophic levels represent links Trophic levels represent links in the chainin the chain

• Trophic Levels are feeding steps Trophic Levels are feeding steps represented in a food chainrepresented in a food chain

• More than one organism can occur in More than one organism can occur in a trophic level depending upon the a trophic level depending upon the chain involvedchain involved

• Each organism is assigned a Each organism is assigned a

trophic leveltrophic level– # of steps away from the sun# of steps away from the sun– members of a trophic level are members of a trophic level are

the same # of steps away from the the same # of steps away from the sunsun

– 11stst trophic level trophic level

•plants and other organisms that plants and other organisms that

make their own foodmake their own food

•i.e., producersi.e., producers

•aka autotrophsaka autotrophs

• 22ndnd trophic level (primary trophic level (primary consumers)consumers)– herbivoresherbivores– plant eatersplant eaters– cows, caterpillars, elephants, cows, caterpillars, elephants,

ducks, etc.ducks, etc.

• 33rdrd trophic level (secondary trophic level (secondary consumers)consumers)– organisms that eat herbivoresorganisms that eat herbivores– carnivorescarnivores– flesh eatersflesh eaters

How Many Trophic Levels?How Many Trophic Levels?

• At each trophic levelAt each trophic level– energy stored in organisms is energy stored in organisms is

1/10 of the energy stored in 1/10 of the energy stored in organisms in the level beloworganisms in the level below

– An ecosystem can hold 5 trophic An ecosystem can hold 5 trophic levels at the mostlevels at the most

– Fewer organisms at higher trophic Fewer organisms at higher trophic levels than at lower trophic levelslevels than at lower trophic levels

•1000 zebras, gazelles, and 1000 zebras, gazelles, and wildebeest for each lionwildebeest for each lion

Food websFood webs

• Food Webs: a representation of all Food Webs: a representation of all possible feeding relationshipspossible feeding relationships

• Food webs are more realistic than Food webs are more realistic than food chains because most organisms food chains because most organisms feed on more than one speciesfeed on more than one species

Energy PyramidEnergy Pyramid

• An An energy pyramidenergy pyramid provides a means of provides a means of describing the feeding and energy describing the feeding and energy relationships within a food chain or relationships within a food chain or web.     web.     

• The transmission of energy from one The transmission of energy from one section of the pyramid to the next is only section of the pyramid to the next is only about 10%about 10%

• Organisms use some energy for: Organisms use some energy for: metabolism, building body tissues, and metabolism, building body tissues, and some is given off as waste.some is given off as waste.

Habitat & NicheHabitat & Niche•HabitatHabitat is the is the

place a plant or place a plant or animal livesanimal lives

•NicheNiche is an is an organism’s organism’s total total way of lifeway of life

The Nonliving EnvironmentThe Nonliving Environment

•Abiotic factorsAbiotic factors- the - the nonliving parts of an nonliving parts of an organism’s environment.organism’s environment.

•Examples Examples include air include air currents, temperature, currents, temperature, moisture, light, and soil.moisture, light, and soil.

•Abiotic factors Abiotic factors affect an affect an organism’s life.organism’s life.

The Living EnvironmentThe Living Environment

•Biotic factorsBiotic factors- all the - all the living organisms that living organisms that inhabit an environment.inhabit an environment.

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

Abiotic or Biotic?Abiotic or Biotic?

BioticBiotic

Abiotic or Biotic?Abiotic or Biotic?

AbioticAbiotic

Abiotic or Biotic?Abiotic or Biotic?

AbioticAbiotic

Abiotic or Biotic?Abiotic or Biotic?

BioticBiotic

Levels of Levels of OrganizationOrganization

What are the Simplest Levels?What are the Simplest Levels?

•AtomAtom•MoleculeMolecule•OrganelleOrganelle•CellCell•TissueTissue•OrganOrgan•SystemSystem

Levels of OrganizationLevels of Organization•EcologistsEcologists have organized the have organized the

interactions an organism takes interactions an organism takes part in into part in into different levels different levels according to complexityaccording to complexity..

11stst Level of Organization Level of Organization•Organism:Organism:

An individual An individual living thing that living thing that is made of is made of cells, cells, uses energy, uses energy, reproduces, reproduces, responds, responds, grows, and grows, and developsdevelops

22ndnd Level of Organization Level of Organization•Population:Population:

A group of A group of organisms, all organisms, all of the of the same same speciesspecies, which , which interbreedinterbreed and and live in the live in the same place at same place at the same the same timetime..

33rdrd Level of Organization Level of Organization•Biological Biological

Community:Community:All the All the populations of populations of different different speciesspecies that that live in the live in the same place at same place at the same time.the same time.

44thth Level of Organization Level of Organization•Ecosystem:Ecosystem:

Populations of Populations of plants and animals plants and animals that interact with that interact with each other in a each other in a given area with the given area with the abiotic components abiotic components of that area. of that area. (terrestrial or (terrestrial or aquatic)aquatic)

55thth Level of Organization Level of Organization

•Biosphere:Biosphere:The The portion of portion of Earth that Earth that supports supports life.life.

The BiosphereThe Biosphere

•Life is found in air, on land, Life is found in air, on land, and in fresh and salt water.and in fresh and salt water.

•The The BIOSPHERE BIOSPHERE is the is the portion of Earth that portion of Earth that supports living things.supports living things.

BiomesBiomes

• AquaticAquatic– FreshwaterFreshwater– SaltwaterSaltwater

• TerrestrialTerrestrial– TundraTundra– DesertDesert– Grassland/SavannaGrassland/Savanna– Temperate ForestTemperate Forest– Tropical Rain ForestTropical Rain Forest– Boreal ForestBoreal Forest

Marine BiomesMarine Biomes

• The oceans have the largest amount The oceans have the largest amount of living material of all the biomes on of living material of all the biomes on earth (mainly microscopic)earth (mainly microscopic)

• Ecologists study the biomes of water Ecologists study the biomes of water in two zones: photic (where most life in two zones: photic (where most life exists), aphoticexists), aphotic

Terrestrial EcosystemsTerrestrial Ecosystems

• Different biomes have different Different biomes have different physical characteristicsphysical characteristics– determines the types of plants and determines the types of plants and

animals that live thereanimals that live there

Tropical Rain ForestsTropical Rain Forests

• Warm, moist climate w/ 100” rainfall in a yearWarm, moist climate w/ 100” rainfall in a year• No variation in temp. or rainfallNo variation in temp. or rainfall• More species than any other biomeMore species than any other biome

– contain ½ of the Earth’s species of land-dwelling contain ½ of the Earth’s species of land-dwelling organismsorganisms

• Exist mainly on infertile soil (nutrients held by Exist mainly on infertile soil (nutrients held by plants)plants)

• Destruction of rainforests will lead to species Destruction of rainforests will lead to species extinctionextinction– most rainforests will be gone w/in 40 yearsmost rainforests will be gone w/in 40 years

Tropical Rain ForestsTropical Rain Forests

SavannasSavannas

• Hot, w/ alternating wet and dry Hot, w/ alternating wet and dry seasonsseasons

• 36 – 60 inches of rain36 – 60 inches of rain

• Great, dry grasslandsGreat, dry grasslands

• Found in tropical areasFound in tropical areas

• Wider extremes in temperatureWider extremes in temperature

• Open landscape w/ widely spaced treesOpen landscape w/ widely spaced trees

SavannasSavannas

DesertsDeserts

• Very hot and dry, 8” rain in a yearVery hot and dry, 8” rain in a year

• Desert organisms have adaptations Desert organisms have adaptations that allow them to conserve waterthat allow them to conserve water

• Vegetation is very sparseVegetation is very sparse

• <5% of N. America is desert<5% of N. America is desert

DesertDesert

Temperate GrasslandsTemperate Grasslands

• Dry, hot summers, cold wintersDry, hot summers, cold winters

• 4-24 inches of rain in a year4-24 inches of rain in a year

• aka prairieaka prairie

• Once covered much of the interior of Once covered much of the interior of N. America, Europe, Asia, and South N. America, Europe, Asia, and South America America

Temperate GrasslandsTemperate Grasslands

Temperate Deciduous ForestsTemperate Deciduous Forests

• Warm summers, cool to cold Warm summers, cool to cold winters (relatively mild climates)winters (relatively mild climates)

• 30 – 100 inches of rain distributed 30 – 100 inches of rain distributed evenly throughout a yearevenly throughout a year

Coniferous ForestsConiferous Forests

• Cool, short summers, cold, long wintersCool, short summers, cold, long winters• 8-24 inches of rainfall in a year, usually 8-24 inches of rainfall in a year, usually

in summerin summer• Conifers, needle-leaved evergreensConifers, needle-leaved evergreens• Marshes, lakes, and ponds commonMarshes, lakes, and ponds common• Dense stands of only one or two speciesDense stands of only one or two species• Large mammals like elk, moose, and Large mammals like elk, moose, and

deerdeer

TundraTundra

• Cold, long winters, cool, short summersCold, long winters, cool, short summers• 10 inches precipitation in a year10 inches precipitation in a year• Between coniferous forests and the Between coniferous forests and the

permanent icepermanent ice• Open, wind-sweptOpen, wind-swept• Covers 1/5 of the Earth’s land surfaceCovers 1/5 of the Earth’s land surface• Water is usually frozenWater is usually frozen• Grasses, sedges, dwarf willows, and mossesGrasses, sedges, dwarf willows, and mosses• Foxes, lemmings, owls, and caribouFoxes, lemmings, owls, and caribou

TundraTundra

Energy PyramidEnergy Pyramid

• The pyramid also shows that much of The pyramid also shows that much of the energy is lost when one organism in the energy is lost when one organism in a food chain eats another.   a food chain eats another.  

• Most of this energy which is lost goes Most of this energy which is lost goes into the environment as heat energy.   into the environment as heat energy.  

• While a continuous input of energy from While a continuous input of energy from sunlight keeps the process going, the sunlight keeps the process going, the height of energy pyramids (and height of energy pyramids (and therefore the length of food chains) is therefore the length of food chains) is limited by this loss of energy. limited by this loss of energy.

Energy PyramidEnergy Pyramid

DecomposersDecomposers• aka aka detritivores detritivores -consumers that get their energy -consumers that get their energy

from detritus-nonliving organic materialfrom detritus-nonliving organic material– Dead organisms, feces, leaf litter, woodDead organisms, feces, leaf litter, wood– Bacteria, fungi, animals which feed on detritus like Bacteria, fungi, animals which feed on detritus like

earthwormsearthworms

• Decompose organic material in ecosystem and Decompose organic material in ecosystem and transfer chemical elements in inorganic forms to transfer chemical elements in inorganic forms to reservoirs such as soil, water, and airreservoirs such as soil, water, and air

• Decomposition by bacteria and fungi accounts for Decomposition by bacteria and fungi accounts for most conversion of organic materials from all trophic most conversion of organic materials from all trophic levels to inorganic compounds usable by primary levels to inorganic compounds usable by primary producers (thereby closing the loop of nutrient cycling)producers (thereby closing the loop of nutrient cycling)

Energy FlowEnergy Flow

• Energy flows through ecosystems, Energy flows through ecosystems, while matter cycles within themwhile matter cycles within them

• Resources critical to human survival Resources critical to human survival and welfare, ranging from the food and welfare, ranging from the food we eat to the oxygen we breathe, are we eat to the oxygen we breathe, are products of ecosystem processesproducts of ecosystem processes

Nutrient Cycling in Nutrient Cycling in EcosystemsEcosystems• Within an ecosystem nutrients are cycled Within an ecosystem nutrients are cycled

internally, there are leaks (outputs) like internally, there are leaks (outputs) like erosion and timber/crop harvesterosion and timber/crop harvest

• Must be replaced by nutrient inputs:Must be replaced by nutrient inputs:– Weathering of rocksWeathering of rocks– Windblown dustWindblown dust– PrecipitationPrecipitation– Decomposition into form available to plantsDecomposition into form available to plants

• Water isWater is

• Evaporated into Evaporated into atmosphere or atmosphere or through through Transpiration Transpiration (lose water from (lose water from plant leaves)plant leaves)

• Condenses into Condenses into cloudsclouds

• Precipitates on Precipitates on land (rain, snow, land (rain, snow, sleet, hail)sleet, hail)

• Cellular Cellular respiration, respiration, burning of burning of fossil fuels fossil fuels contribute to contribute to Carbon in the Carbon in the atmosphereatmosphere

• PhotosynthesiPhotosynthesis of plants s of plants takes it out.takes it out.

• Atmosphere Atmosphere is 78% is 78% nitrogennitrogen

• Bacteria Bacteria can fix can fix nitrogen nitrogen (nitrogen-(nitrogen-fixation) for fixation) for plant useplant use

• Lightning Lightning can also can also change change nitrogen nitrogen into a into a usable usable form.form.

• Phosphorus Phosphorus is used by is used by plants, fungi plants, fungi and other and other organismsorganisms

• Comes from Comes from the the weathering weathering of rock, of rock, leaching of leaching of the soil, and the soil, and waste from waste from organismsorganisms

Nutrient Cycling in Nutrient Cycling in EcosystemsEcosystems• Nutrients are carried from terrestrial Nutrients are carried from terrestrial

ecosystems by movement of water and ecosystems by movement of water and deposited in aquatic ecosystems and deposited in aquatic ecosystems and associated lowlandsassociated lowlands

• If inputs exceed outputs, the nutrient If inputs exceed outputs, the nutrient cycle in the ecosystem becomes stressed cycle in the ecosystem becomes stressed or overloaded resulting in pollution or overloaded resulting in pollution (nutrient levels exceed capability of the (nutrient levels exceed capability of the ecosystem to process them)ecosystem to process them)

Nutrient Cycling in Nutrient Cycling in EcosystemsEcosystems• Nutrients eroded from agricultural lands, Nutrients eroded from agricultural lands,

sewage, industrial wastes drain into sewage, industrial wastes drain into streams, rivers, lakes and estuariesstreams, rivers, lakes and estuaries

• These pollutants destroy plants and These pollutants destroy plants and animals that cannot tolerate their animals that cannot tolerate their presence or the changed environmental presence or the changed environmental conditions caused by themconditions caused by them

Organisms and Organisms and Their EnvironmentTheir Environment

Interactions within populationsInteractions within populations

• Population: a group of organisms of Population: a group of organisms of the same species that interbreed and the same species that interbreed and live in the same place at the same live in the same place at the same timetime

• Members of populations compete for Members of populations compete for resources resources

• Competition occurs when resources Competition occurs when resources are in short supplyare in short supply

• Competition is dependent upon the Competition is dependent upon the organisms adaptationsorganisms adaptations

Individuals interact within Individuals interact within communitiescommunities

• Community: Made up of many populations Community: Made up of many populations of organismsof organisms

• A change in one population effects other A change in one population effects other populations in the communitypopulations in the community

• The number of organisms is importantThe number of organisms is important

• Numbers can change due to predation or a Numbers can change due to predation or a change in resourceschange in resources

Living RelationshipsLiving Relationships

• In order to better survive in their In order to better survive in their environment species form environment species form relationshipsrelationships

• Previous thought: all organisms were Previous thought: all organisms were in competition for the environmentin competition for the environment

• Current thought: two types of Current thought: two types of relationships include Predator/Prey relationships include Predator/Prey and Symbiotic Relationshipsand Symbiotic Relationships

Predator/Prey RelationshipsPredator/Prey Relationships

•Predators: Animals that kill and Predators: Animals that kill and eat other predatorseat other predators

•Prey: Animals that are killed or Prey: Animals that are killed or eateneaten

Carrying CapacityCarrying Capacity

• All ecosystems are All ecosystems are said to have a said to have a carrying capacitycarrying capacity

• CC is the amount of CC is the amount of organisms an organisms an ecosystem can ecosystem can sustain.sustain.

• If input exceeds If input exceeds output, a species or output, a species or ecosystem may ecosystem may crashcrash

CompetitionCompetition

• Organisms living in Organisms living in the same area or the same area or sharing a niche will sharing a niche will compete with each compete with each other for resourcesother for resources

• Which organism Which organism out competed the out competed the other?other?

Symbiotic RelationshipsSymbiotic Relationships• Symbiosis: A close and permanent Symbiosis: A close and permanent

relationships among organisms who are living relationships among organisms who are living togethertogether

• Commensalism: A specific type of symbiotic Commensalism: A specific type of symbiotic relationship in which only one species benefits relationship in which only one species benefits and the other is neither helped or hurtand the other is neither helped or hurt

• Mutualism: A symbiotic relationship in which Mutualism: A symbiotic relationship in which both organisms benefitboth organisms benefit

• Parasitism: One organism benefits at the Parasitism: One organism benefits at the expense of the other without killing the hostexpense of the other without killing the host

ParasitismParasitism

• Parasites feed on their hosts such Parasites feed on their hosts such as viruses or bacteriaas viruses or bacteria– does not kill its hostdoes not kill its host– usually smaller than the organism usually smaller than the organism

on which it feedson which it feeds

MutualismMutualism

• All participating species benefitAll participating species benefit– Lichen is composed of a fungus and a Lichen is composed of a fungus and a

green algagreen alga•the fungus absorbs nutrients for both the fungus absorbs nutrients for both

partnerspartners

•the algae carries out photosynthesis to the algae carries out photosynthesis to provide food for itself and the fungusprovide food for itself and the fungus

– Nitrogen fixing bacteria live in the roots Nitrogen fixing bacteria live in the roots of plantsof plants•bacteria get a place to livebacteria get a place to live

•bacteria provide the plants w/ useable bacteria provide the plants w/ useable nitrogennitrogen

Mutualism and Mutualism and E.coliE.coli

• The bacteria The bacteria Eschericia coliEschericia coli live in live in our intestinesour intestines– bacteria have access to foodbacteria have access to food– bacteria provide us with Vitamin K bacteria provide us with Vitamin K

(necessary for blood clotting)(necessary for blood clotting)

CommensalismCommensalism

• One species benefits One species benefits while the other species is not affectedwhile the other species is not affected

– Boxing crab and anemonesBoxing crab and anemones•crab wears anemones for protectioncrab wears anemones for protection•no apparent harm or benefit for no apparent harm or benefit for anemonesanemones

– Whales and barnaclesWhales and barnacles•barnacles get a ride and barnacles get a ride and protectionprotection•no harm, no benefit for whaleno harm, no benefit for whale

Succession Defined:

• Change in the abundances of the dominant species in a community following a disturbance.

• Primary succession: beginning from a abiotic environment following a major disturbance (glacier, earthquake, fire, logging).

• Secondary succession: beginning from a major disturbance, but all forms of life are not destroyed (tornado, fire, flooding, disease, farming, snow meltoff).

Stages of Succession• Early: plants typically small with short

lifecycles (annuals…), rapid seed dispersal, environmental stabilizers (pioneer species)

• Middle: plants typically longer lived, slower seed dispersal, and in woodland systems: larger. Shrubs, bushes

• Late: plants and animal species are those associated with older, more mature ecosystem. Conifers, birds, deer

• Climax: (120 years) The full amount of plants and animals in an area. Deciduous trees, bears, deer, conifers, ferns, birds, etc.

• Primary Primary Succession Succession after the after the retreat of a retreat of a glacier. glacier. Pioneer Pioneer species are species are the first to the first to inhabit the inhabit the area.area.

• Secondary Secondary Succession Succession from an from an abandoned abandoned cornfield. cornfield. Annuals and Annuals and shrubs may shrubs may sprout sprout immediatelyimmediately. .

© 2003 John Wiley and Sons Publishers

Fig 10.7 Diagram Fig 10.7 Diagram of bog succession.of bog succession.

© 2003 John Wiley and Sons Publishers

Fig 10.8 Graphs Fig 10.8 Graphs showing changes showing changes in biomass and in biomass and diversity with diversity with succession.succession.

Plants that are Plants that are more fit to more fit to survive will survive will out compete out compete other species other species and dominant and dominant the ecosystemthe ecosystem..