Ecology NotesEcology Notes

DefinitionsDefinitions

• EcologyEcology: the study of the interactions : the study of the interactions among organisms and their environment.among organisms and their environment.

• Biotic FactorsBiotic Factors: living parts of the : living parts of the environment (Ex: plants, animals, fungi, environment (Ex: plants, animals, fungi, etc)etc)

• Abiotic FactorsAbiotic Factors: non-living parts of the : non-living parts of the environment (Ex: temperature, light, pH)environment (Ex: temperature, light, pH)

Levels of OrganizationLevels of Organization• OrganismOrganism (Ex: a fish) (Ex: a fish)

• SpeciesSpecies – a group of the same kind of – a group of the same kind of organism that can successfully interbreedorganism that can successfully interbreed

• PopulationPopulation – group of the same species living – group of the same species living in the same placein the same place– All the red squirrels in a forestAll the red squirrels in a forest

• CommunityCommunity – all of the different organisms in – all of the different organisms in a habitata habitat– All of the trees, plants, animals, bacteria in the All of the trees, plants, animals, bacteria in the

forestforest

• EcosystemEcosystem – includes biotic and abiotic – includes biotic and abiotic factorsfactors– The whole forest, including the river, air, weatherThe whole forest, including the river, air, weather

Trophic (Energy) Levels in an Trophic (Energy) Levels in an EcosystemEcosystem

• ProducersProducers – make their own food, – make their own food, like plantslike plants– aka: aka: autotrophs (self feeders)autotrophs (self feeders)

• ConsumersConsumers – obtain – obtain energy by feeding on energy by feeding on another organism, likeanother organism, like animals animals– aka: aka: heterotrophs heterotrophs

(other feeders)(other feeders)

• DecomposersDecomposers – – break down dead organisms, like fungus and break down dead organisms, like fungus and bacteriabacteria

Food ChainFood Chain

• The path of food The path of food transfer from one transfer from one trophic level to trophic level to anotheranother

• ArrowsArrows go in the go in the direction of direction of energy flow!energy flow!

Food Chain VideoFood Chain Video

Types of consumersTypes of consumers

• HerbivoreHerbivore – eats only producers – eats only producers– Example: rabbitExample: rabbit

• CarnivoreCarnivore – eats only other consumers – eats only other consumers– Example: wolfExample: wolf

• OmnivoreOmnivore – eats both producers and – eats both producers and consumersconsumers– Example: humansExample: humans

• DecomposerDecomposer – breaks down dead or decaying – breaks down dead or decaying organic matterorganic matter– Example: fungi and bacteriaExample: fungi and bacteria

• ScavengerScavenger – eats whatever it can find, – eats whatever it can find, leftovers from already hunted animals, plants, leftovers from already hunted animals, plants, etcetc– Example: crabs, vultures, and hyenasExample: crabs, vultures, and hyenas

Food WebsFood Webs• A set of inter-A set of inter-

connected food chainsconnected food chains

• If one organism is If one organism is removed, all the removed, all the others will be affected.others will be affected.– If we remove the If we remove the

mouse, then the mouse, then the grasshopper population grasshopper population will rise, but the owl will rise, but the owl population will decreasepopulation will decrease

Energy Pyramid VideoEnergy Pyramid Video

Energy PyramidsEnergy Pyramids• Emphasizes the energy loss from one trophic level to the Emphasizes the energy loss from one trophic level to the

next. In general, next. In general, 10%10% of the energy available at one of the energy available at one level is transferred to the next level during feeding.level is transferred to the next level during feeding.

• The remaining The remaining 90% is either used by the organisms 90% is either used by the organisms during its life or it is lost as heat. during its life or it is lost as heat.

10% Energy

90 %

Energy

• Biomass PyramidBiomass Pyramid - Represents the actual biomass (dry - Represents the actual biomass (dry mass of all organisms in each trophic level) in an mass of all organisms in each trophic level) in an ecosystem. ecosystem.

• Pyramid of NumbersPyramid of Numbers - Depicts the number of - Depicts the number of individual organisms in each trophic level of an individual organisms in each trophic level of an ecosystemecosystem

• Notice that both usually look just like the energy Notice that both usually look just like the energy pyramidpyramid

Population GrowthPopulation Growth

• Exponential Exponential GrowthGrowth - when a - when a population grows population grows with no limitswith no limits– For instance, the For instance, the

population population doubles every 2 doubles every 2 yearsyears

• Graph is in shape Graph is in shape of a of a J –curveJ –curve

HumanHuman

Today, we are adding 82 million people/year,~ 200,000 per day!

Today, we are adding 82 million people/year,~ 200,000 per day!

Non-native speciesNon-native species– Grow exponentiallyGrow exponentially– populations introduced to populations introduced to

a new habitat out-a new habitat out-compete native species compete native species • No natural predators or No natural predators or

parasitesparasites

• reduce diversity of habitatreduce diversity of habitat

– examplesexamples• African honeybeeAfrican honeybee

• gypsy mothgypsy moth

gypsy mothgypsy moth

reduces diversity loss of food & nesting sites

for animals Cause economic damage

reduces diversity loss of food & nesting sites

for animals Cause economic damage

Logistic GrowthLogistic Growth

• Carrying CapacityCarrying Capacity – – thethe maximum maximum number number ofof organisms an organisms an enenvironment can vironment can susupportpport– Determined by Determined by

amount of food, amount of food, space, or resourcesspace, or resources

• Creates an Creates an S-shaped S-shaped curvecurve– More realisticMore realistic

Is the human population reaching its

carrying capacity?

Predator-Prey CyclesPredator-Prey Cycles

The size of the predator population limits the size of the prey population and vice versa

Species InteractionsSpecies Interactions

• NicheNiche – an organism’s “job” or role in – an organism’s “job” or role in the ecosystemthe ecosystem– DecomposerDecomposer– Carnivore Carnivore – Top predator, etc.Top predator, etc.

Predation (+,-)Predation (+,-)

• One individual (predator) captures, One individual (predator) captures, kills, and consumes another (prey)kills, and consumes another (prey)

• Predation limits the size of the prey Predation limits the size of the prey populationpopulation

Examples of predationExamples of predation

• Lion and zebra Red-tailed Lion and zebra Red-tailed hawk and hawk and

rodentrodent

Competition (-,-)Competition (-,-)

• Results from 2 species occupying the Results from 2 species occupying the same nichesame niche– the use of the same limited resource by the use of the same limited resource by

two or more speciestwo or more species

Example of competitionExample of competition• Barnacles competing for space Barnacles competing for space

• 2 carnivores compete for feeding territory2 carnivores compete for feeding territory

Parasitism (+,-)Parasitism (+,-)

• One individual (host) is harmed, One individual (host) is harmed, while the other individual (parasite) while the other individual (parasite) benefitsbenefits

• Does not usually result in death of Does not usually result in death of host – the parasite would have to go host – the parasite would have to go find a new home!find a new home!

Examples of ParasitismExamples of Parasitism

• Tick and HumanTick and Human • Flea and DogFlea and Dog

Mutualism (+,+)Mutualism (+,+)

• Cooperative relationship where both Cooperative relationship where both species benefitspecies benefit

• Often species cannot survive as well Often species cannot survive as well without each otherwithout each other

Examples of mutualismExamples of mutualism

• Rhino and Rhino and oxpeckeroxpecker

• Flower and bee Flower and bee (pollination)(pollination)

Commensalism (+,0)Commensalism (+,0)

• One species benefits, the other is not One species benefits, the other is not affectedaffected

Examples of commensalismExamples of commensalism

• Cattle Egret and Cattle Egret and Cape BuffaloCape Buffalo

• Remora and sharkRemora and shark

Name that interaction…Name that interaction…

• Honey guide birds alert and direct Honey guide birds alert and direct badgers to bee hives. The badgers badgers to bee hives. The badgers then expose the hives and feed on then expose the hives and feed on the honey first. Next the honey the honey first. Next the honey guide birds eat. Both species guide birds eat. Both species benefit.benefit.

MutualismMutualism

Name that interaction…Name that interaction…

• Mistletoe extracts water and Mistletoe extracts water and nutrients from a spruce tree to the nutrients from a spruce tree to the tree’s detriment.tree’s detriment.

ParasitismParasitism

Name that interaction…Name that interaction…• Barnacles create home sites by Barnacles create home sites by

attaching themselves to whales. This attaching themselves to whales. This relationship neither harms nor benefits relationship neither harms nor benefits the whales.the whales.

CommensalismCommensalism

Ecological SuccessionEcological Succession• How a community changes over timeHow a community changes over time

– For example from a grassland to a forestFor example from a grassland to a forest

• Occurs as one group of species (a Occurs as one group of species (a community) outcompetes and replaces an community) outcompetes and replaces an older communityolder community

Stages of SuccessionStages of Succession

Primary SuccessionPrimary Succession• No life, no soil before.No life, no soil before.

– Ex. – glaciers melt off of a bare rockEx. – glaciers melt off of a bare rock• Pioneer speciesPioneer species: the first species to colonize an : the first species to colonize an

area – usually lichens & mossarea – usually lichens & moss• Climax communityClimax community: a mature, stable community : a mature, stable community

with high biodiversity and little changewith high biodiversity and little change

Secondary SuccessionSecondary Succession• Already life, already soilAlready life, already soil

• Ex. - Abandoned field , or forest after wildfiresEx. - Abandoned field , or forest after wildfires

• Pioneer species would be weeds and grassesPioneer species would be weeds and grasses

• Secondary happens fasterSecondary happens faster

Secondary Sucession (cont.)Secondary Sucession (cont.)Another example is a pond in a forest slowly fills in with silt, becoming a field then eventually a forestCan you put these pictures in the correct order?

Environmental IssuesEnvironmental Issues

• Global Climate ChangeGlobal Climate Change– Caused by excess Caused by excess

release of COrelease of CO22

•From burning of fossil From burning of fossil fuelsfuels

– Occurs slowly over Occurs slowly over many yearsmany years•Yearly fluctuations in Yearly fluctuations in

temp are temp are notnot evidence for or evidence for or against global against global climate changeclimate change

Human-caused changes in the ecosystem

Ozone LayerOzone Layer• Protects us from harmful Protects us from harmful

UV raysUV rays

• Has been thinned to Has been thinned to dangerous levelsdangerous levels– Due to release of CFC’sDue to release of CFC’s

• From aerosol cans and cooling From aerosol cans and cooling

• Has led to significant Has led to significant increase in skin cancerincrease in skin cancer

Acid RainAcid Rain– Coal-burning plants and cars release Coal-burning plants and cars release

nitrogen and sulfur into the atmosphere nitrogen and sulfur into the atmosphere – Leads to more acidic precipitation (lower Leads to more acidic precipitation (lower

pH)pH)

Normal Rain

Acid Rain

The EndThe End