Ecosystems and CommunitiesEcosystems and CommunitiesInterdependence in NatureInterdependence in Nature

Chapter 4Chapter 4

ClimateClimate

Weather vs. climateWeather vs. climate– Both measure of temperature and precipitationBoth measure of temperature and precipitation

Day-to-day = weatherDay-to-day = weather Average conditions over long period = climateAverage conditions over long period = climate

Climate is NOT uniform within a regionClimate is NOT uniform within a region– Microclimates – important to many organisms Microclimates – important to many organisms

but not necessarily readily noticeablebut not necessarily readily noticeable

Factors that Affect ClimateFactors that Affect Climate

Solar energySolar energy– Greenhouse effect – certain gases allow light to Greenhouse effect – certain gases allow light to

enter atmosphere but trap heatenter atmosphere but trap heat LatitudeLatitude

– Amount of direct sunlight received decreases Amount of direct sunlight received decreases as we move from equator to polesas we move from equator to poles

– Causes tropical, temperate and polar regionsCauses tropical, temperate and polar regions Transport of heatTransport of heat

– Wind Wind warm air rises, cold air sinks warm air rises, cold air sinks– Ocean currentsOcean currents

NichesNiches

Tolerance – the ability to survive and Tolerance – the ability to survive and reproduce under a range of environmental reproduce under a range of environmental conditionsconditions– Every organism has an upper and lower limit Every organism has an upper and lower limit – Helps determine habitat – the general place Helps determine habitat – the general place

where an organism lives (the “address”)where an organism lives (the “address”) Niche – the “job” of the organism (both Niche – the “job” of the organism (both

where and how)where and how)– Resources – any necessity of lifeResources – any necessity of life– Contains both biotic and abiotic factorsContains both biotic and abiotic factors

CompetitionCompetition

Occurs when organisms attempt to Occurs when organisms attempt to use the same limited resourcesuse the same limited resources– Both among species (intraspecific) and,Both among species (intraspecific) and,– Between different species (interspecific)Between different species (interspecific)

Competitive exclusion principle – no Competitive exclusion principle – no two species can occupy exactly the two species can occupy exactly the same nichesame niche

Predation, Herbivory, and Keystone Predation, Herbivory, and Keystone SpeciesSpecies

Predation – predator captures and Predation – predator captures and feeds on preyfeeds on prey

Herbivory – herbivore feeds on Herbivory – herbivore feeds on producers (plants)producers (plants)

Keystone species – single species Keystone species – single species that can cause dramatic changes in that can cause dramatic changes in the community based on presence or the community based on presence or absence absence

SymbiosesSymbioses

Relationship where two species live Relationship where two species live closely togetherclosely together

Three major typesThree major types– Mutualism – everybody wins (both Mutualism – everybody wins (both

organisms benefit from interaction)organisms benefit from interaction)– Parasitism – I win, you lose (harm or Parasitism – I win, you lose (harm or

death)death)– Commensalism – I win, you get nothing Commensalism – I win, you get nothing

and like it! (no harm or help)and like it! (no harm or help)

SuccessionSuccession

Ecological succession – series of Ecological succession – series of changes that occur in a community changes that occur in a community over timeover time

Primary vs. SecondaryPrimary vs. Secondary– Primary – an area where no community Primary – an area where no community

remains (a clean start)remains (a clean start)Pioneer species – first to colonize a barren Pioneer species – first to colonize a barren

areaarea

– Secondary – an area where disturbance Secondary – an area where disturbance has occurred (fire or disaster)has occurred (fire or disaster)