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Chapter 50Chapter 50

An Introduction to Ecology and the An Introduction to Ecology and the BiosphereBiosphere

The Scope of EcologyThe Scope of Ecology

Ecology is the scientific study of the interactions Ecology is the scientific study of the interactions interactionsinteractions determine distribution of organisms determine distribution of organisms and their abundanceand their abundanceEcology reveals the richness of the biosphere Ecology reveals the richness of the biosphere between organisms and the environmentbetween organisms and the environment–– Early science was basically ecologyEarly science was basically ecology–– New methods and computers have made ecology one of New methods and computers have made ecology one of

the more rigorous and robust sciencesthe more rigorous and robust sciences

Ecology and Evolutionary Ecology and Evolutionary BiologyBiology

Events that occur in ecological time affect Events that occur in ecological time affect life on the scale of evolutionary timelife on the scale of evolutionary timeThe environment is constantly weeding out The environment is constantly weeding out less fit individualsless fit individualsAs the environment changes, so do the As the environment changes, so do the populations of organisms populations of organisms

Organisms and the Organisms and the EnvironmentEnvironment

The environment of any The environment of any organism includes:organism includes:–– Abiotic, or nonliving, Abiotic, or nonliving,

componentscomponents–– Biotic, or living, componentsBiotic, or living, components

•• All the organisms that are All the organisms that are part of the individualpart of the individual’’s s environment are collectively environment are collectively called the biotacalled the biota

•• Environmental components Environmental components affect the distribution and affect the distribution and abundance of organismsabundance of organisms

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Subfields of EcologySubfields of EcologyOrganismalOrganismal ecology studies how an ecology studies how an organismorganism’’s structure, physiology, and (for s structure, physiology, and (for animals) behavior meet environmental animals) behavior meet environmental challengeschallenges

Population EcologyPopulation EcologyPopulation ecology focuses Population ecology focuses on factors affecting how on factors affecting how many individuals of a many individuals of a species live in an areaspecies live in an area

Community ecology deals with the whole Community ecology deals with the whole array of interacting species in a communityarray of interacting species in a community

Community EcologyCommunity Ecology

Ecosystem ecology emphasizes energy flow Ecosystem ecology emphasizes energy flow and chemical cycling among the various and chemical cycling among the various biotic and abiotic componentsbiotic and abiotic components

Ecosystem EcologyEcosystem Ecology

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Landscape ecology deals with arrays of Landscape ecology deals with arrays of ecosystems and how they are arranged in a ecosystems and how they are arranged in a geographic regiongeographic region

Landscape EcologyLandscape Ecology

Ecology and Environmental Ecology and Environmental IssuesIssues

Ecology provides the Ecology provides the scientific understanding scientific understanding underlying environmental underlying environmental issuesissuesRachel Carson is credited Rachel Carson is credited with starting the modern with starting the modern environmental movementenvironmental movementMost ecologists follow the Most ecologists follow the precautionary principle precautionary principle regarding environmental regarding environmental issuesissues

Interactions between organisms and the environment Interactions between organisms and the environment determine the distribution of speciesdetermine the distribution of species

Ecologists have long recognized global and regional Ecologists have long recognized global and regional patterns of distribution of organisms within the biospherepatterns of distribution of organisms within the biosphere–– BiogeographicBiogeographic realms realms -- BiogeographyBiogeography

Flowchart of Factors limiting Flowchart of Factors limiting geographic distributiongeographic distribution

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Dispersal and DistributionDispersal and DistributionDispersal is movement of individuals away from Dispersal is movement of individuals away from centers of high population density or from their centers of high population density or from their area of originarea of originDispersalDispersal contributes to global distribution of contributes to global distribution of organismsorganismsIf a species is absent from an area If a species is absent from an area Why?Why?

Natural Range ExpansionsNatural Range ExpansionsNatural range expansions show the Natural range expansions show the influence of dispersal on distributioninfluence of dispersal on distribution–– Cattle EgretsCattle Egrets–– BrownBrown--headed Cowbirdsheaded Cowbirds

Species TransplantsSpecies TransplantsSpecies transplants include organisms that are Species transplants include organisms that are intentionally or accidentally relocated from their intentionally or accidentally relocated from their original distributionoriginal distributionSpecies transplantsSpecies transplants can disrupt the communities or can disrupt the communities or ecosystems to which they have been introducedecosystems to which they have been introduced

Behavior and Habitat SelectionBehavior and Habitat Selection

Some organisms do not occupy all of their Some organisms do not occupy all of their potential rangepotential rangeSpecies distribution may be limited by Species distribution may be limited by habitat selection behaviorhabitat selection behavior

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Biotic FactorsBiotic Factors

Biotic factors that affect the distribution of Biotic factors that affect the distribution of organisms may include:organisms may include:–– Interactions with other speciesInteractions with other species–– PredationPredation–– CompetitionCompetition

Abiotic FactorsAbiotic FactorsAbiotic factors affecting distribution of organisms:Abiotic factors affecting distribution of organisms:–– TemperatureTemperature affects biological processesaffects biological processes–– WaterWater availability in habitats is another important factor availability in habitats is another important factor

in species distributionin species distribution–– SunlightSunlight

Light intensity and quality affects photosynthesisLight intensity and quality affects photosynthesisLight is also important to development and behavior of Light is also important to development and behavior of organisms sensitive to photoperiodorganisms sensitive to photoperiod

–– WindWindWind amplifies effects of temperature by increasing heat loss Wind amplifies effects of temperature by increasing heat loss from evaporation and convectionfrom evaporation and convectionWindWind can change morphology of plantscan change morphology of plants

–– Rocks and soilRocks and soilMany characteristics of soil limit distribution of plants and thMany characteristics of soil limit distribution of plants and thus us the animals that feed upon them:the animals that feed upon them:Physical structurePhysical structurepHpHMineral compositionMineral composition

ClimateClimate

Four major abiotic components of climate: Four major abiotic components of climate: temperaturetemperature, , waterwater, , sunlightsunlight, and , and windwindClimate is the prevailing weather in an areaClimate is the prevailing weather in an areaMacroclimateMacroclimate consists of patterns on the global, consists of patterns on the global, regional, and local levelregional, and local levelMicroclimateMicroclimate consists of very fine patterns, such as consists of very fine patterns, such as those encountered by the community of organisms those encountered by the community of organisms underneath a fallen logunderneath a fallen log

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Global Climate PatternsGlobal Climate PatternsGlobal climate patterns are determined largely by solar Global climate patterns are determined largely by solar energy and the planetenergy and the planet’’s movement in spaces movement in spaceSunlight intensity is a major determinant for EarthSunlight intensity is a major determinant for Earth’’s climate s climate patternspatternsSeasonal variations increase steadily toward the polesSeasonal variations increase steadily toward the poles

Regional, Local, and Seasonal Regional, Local, and Seasonal Effects on ClimateEffects on Climate

Various features of the landscape contribute to local Various features of the landscape contribute to local variations in climatevariations in climateSeasonal variation also influences climateSeasonal variation also influences climateOceansOceans and their and their currentscurrents and and large lakeslarge lakes moderate the moderate the climate of nearby terrestrial environmentsclimate of nearby terrestrial environmentsMountainsMountains have a significant effect onhave a significant effect on–– The amount of sunlight reaching an areaThe amount of sunlight reaching an area–– Local temperatureLocal temperature–– RainfallRainfall

SeasonalitySeasonalityThe angle of the sun leads to many seasonal The angle of the sun leads to many seasonal changes in local environmentschanges in local environmentsLakes are sensitive to seasonal temperature change Lakes are sensitive to seasonal temperature change and experience seasonal turnoverand experience seasonal turnover

LongLong--Term Climate ChangeTerm Climate ChangeOne way to predict future global climate change is to study One way to predict future global climate change is to study previous changesprevious changesBeech trees migrate at 0.2 km/year Beech trees migrate at 0.2 km/year –– too slow to keep up too slow to keep up with climate change with climate change –– must move at 7must move at 7--9 km/year9 km/year

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Abiotic and biotic factors influence the Abiotic and biotic factors influence the structure and dynamics of aquatic biomesstructure and dynamics of aquatic biomes

Varying combinations of biotic and abiotic factors Varying combinations of biotic and abiotic factors determine the nature of biomesdetermine the nature of biomesBiomes are the major ecological associations that Biomes are the major ecological associations that occupy broad geographic regions of land or wateroccupy broad geographic regions of land or waterAquatic biomes account for the largest part of the Aquatic biomes account for the largest part of the biosphere in terms of areabiosphere in terms of areaTheyThey can contain fresh water or salt watercan contain fresh water or salt waterOceans cover about 75% of EarthOceans cover about 75% of Earth’’s surface and s surface and have an enormous impact on the biospherehave an enormous impact on the biosphere

Aquatic Aquatic ZonationZonation

Climate largely determines the Climate largely determines the distribution and structure of distribution and structure of terrestrial biomesterrestrial biomes

Climate is very important in determining why Climate is very important in determining why terrestrial biomes are found in certain areasterrestrial biomes are found in certain areasClimate has a great impact on the distribution of Climate has a great impact on the distribution of organisms, as seen on a organisms, as seen on a climographclimograph

LE 50LE 50--1919

Temperate grassland

Tropic ofCancer

30°N

Tropic ofCapricorn

30°S

Equator

Tropical forest

DesertSavanna

Key Chaparral

Coniferous forestTemperate broadleaf forest

TundraHigh mountainsPolar ice

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ClimagraphClimagraph

General Features of Terrestrial General Features of Terrestrial BiomesBiomes

Terrestrial biomes are often named for major physical or Terrestrial biomes are often named for major physical or climatic factors and for vegetationclimatic factors and for vegetationStratification is a key feature of terrestrial biomesStratification is a key feature of terrestrial biomesTerrestrial biomes usually grade into each other, without Terrestrial biomes usually grade into each other, without sharp boundariessharp boundariesThe area of The area of intergradationintergradation, called an , called an ecotoneecotone, may be wide , may be wide or narrowor narrowMajor terrestrial biomes:Major terrestrial biomes:–– Tropical forestTropical forest–– DesertDesert–– SavannaSavanna–– ChaparralChaparral–– Temperate grasslandTemperate grassland–– Coniferous forestConiferous forest–– Temperate broadleaf forestTemperate broadleaf forest–– TundraTundra

Trop. Forest

Desert

Savanna

Chaparral

GrasslandsConifers

Deciduous

Tundra