Chapter Chapter ##44Ecosystems andEcosystems and

Living (Biotic) OrganismsLiving (Biotic) Organisms(pages 64 – 84)(pages 64 – 84)

Overview of Chapter Overview of Chapter #44o EvolutionEvolution

• Natural SelectionNatural Selection• Domains and KingdomsDomains and Kingdoms

o Biological CommunitiesBiological Communities• Primary & Secondary SuccessionPrimary & Secondary Succession

o SymbiosisSymbiosis• Mutualism, Commensalism, ParasitismMutualism, Commensalism, Parasitism

o Predation & CompetitionPredation & Competitiono Resource PartitioningResource Partitioningo Keystone SpeciesKeystone Specieso Species Richness & Community Species Richness & Community

StabilityStability

Evolution and Natural SelectionEvolution and Natural Selection

o The cumulative genetic changes that The cumulative genetic changes that occur in a population of organisms over occur in a population of organisms over timetime• Current theories were proposed by Charles Current theories were proposed by Charles

Darwin, a 19Darwin, a 19thth century naturalist century naturalist• Evolution occurs through natural selectionEvolution occurs through natural selection

o Natural SelectionNatural Selection• Individuals with more favorable genetic traits Individuals with more favorable genetic traits

are more likely to survive and reproduceare more likely to survive and reproduce• Frequency of favorable traits increase in Frequency of favorable traits increase in

subsequent generationssubsequent generations

Natural SelectionNatural Selection

o Based on four observations about Based on four observations about the natural worldthe natural world

1.1. OverproductionOverproduction• Each species produces more offspring than will Each species produces more offspring than will

survive to maturity (David Lack, 1943)survive to maturity (David Lack, 1943)

2.2. VariationVariation• Individuals in a population exhibit variationIndividuals in a population exhibit variation

3.3. Limits on Population GrowthLimits on Population Growth• Resource limitations will limit populations.Resource limitations will limit populations.

4.4. Differential Reproductive SuccessDifferential Reproductive Success• Individuals with most favorable traits are more Individuals with most favorable traits are more

likely to reproducelikely to reproduce

Natural Natural SelectionSelection

o Darwin’s Darwin’s finches finches exemplified the exemplified the variation variation associated with associated with natural natural selectionselection

Domains and Kingdoms of LifeDomains and Kingdoms of Life

Think of this variation

(diversity) as different

organisms (both plants and

animals) with different traits,

abilities and methods for

surviving and reproducing.

Biological CommunitiesBiological Communities

o Communities vary greatly in size and lack Communities vary greatly in size and lack precise boundariesprecise boundaries• They are often nestled within each other, and They are often nestled within each other, and

dependent upon the abiotic resources in an area.dependent upon the abiotic resources in an area.• Q: How might changes in resource abundance Q: How might changes in resource abundance

affect communities?affect communities?

Interactions Among OrganismsInteractions Among Organisms

o SymbiosisSymbiosis• An intimate relationship between members An intimate relationship between members

of 2 or more speciesof 2 or more species• Participants may be benefited, harmed or Participants may be benefited, harmed or

unaffected by the relationshipunaffected by the relationship• Results of coevolutionResults of coevolution

o Three types of symbiosisThree types of symbiosis• MutualismMutualism• CommensalismCommensalism• ParasitismParasitism

MutualismMutualism

o Symbiotic relationship in which both Symbiotic relationship in which both members benefitmembers benefit

o Ex: Mycorrihzal fungi and plant rootsEx: Mycorrihzal fungi and plant roots• Fungus grows around and into roots providing Fungus grows around and into roots providing

roots with otherwise unavailable nitrogen from roots with otherwise unavailable nitrogen from soilsoil

• Roots provide fungi with food produced by Roots provide fungi with food produced by photosynthesis in the plantphotosynthesis in the plant

LeftLeft: root : root growth without growth without

fungifungi

RightRight: root : root growth with growth with

fungifungi

CommensalismCommensalism

o Symbiotic relationship where one species Symbiotic relationship where one species benefits and the other is neither harmed benefits and the other is neither harmed nor helpednor helped

o Ex: epiphytes and tropical treesEx: epiphytes and tropical trees• Epiphytes anchors Epiphytes anchors

itself to the tree, itself to the tree, but does not take but does not take nutrients from the nutrients from the treetree

• Epiphyte benefits Epiphyte benefits from getting from getting closer to sunlight, closer to sunlight, tropical tree is not tropical tree is not affectedaffected

ParasitismParasitismo Symbiotic relationship in which one Symbiotic relationship in which one

species is benefited and the other is species is benefited and the other is harmedharmed• Parasites rarely kill their hostsParasites rarely kill their hostso Ex: Varroa mites Ex: Varroa mites

and honeybeesand honeybees• Mites live in the Mites live in the

breathing tubes of breathing tubes of the bees, sucking the bees, sucking their blood and their blood and weakening themweakening them

PredationPredationo The consumption of one species by The consumption of one species by

anotheranothero Many predator-prey interactionsMany predator-prey interactions

• Most common is pursuit and ambushMost common is pursuit and ambush

o Plants and animals have established Plants and animals have established specific defenses against predation specific defenses against predation through evolutionthrough evolution

Pursuit and Pursuit and AmbushAmbush

o Pursuing prey simply means chasing it Pursuing prey simply means chasing it down and catching itdown and catching it• Ex: Day gecko and spider (see picture)Ex: Day gecko and spider (see picture)

o Ambush is when predators catch prey Ambush is when predators catch prey unawareunaware• CamouflageCamouflage• Attract prey with Attract prey with

colors or lightcolors or light

Plant Defenses Against Plant Defenses Against PredationPredation

o Plants cannot flee predatorsPlants cannot flee predatorso AdaptationsAdaptations

• Spikes, thorns, leathery leaves, thick waxSpikes, thorns, leathery leaves, thick wax• Protective chemicals that are poisonous or Protective chemicals that are poisonous or

unpalatableunpalatable

Animal Defenses Animal Defenses Against PredationAgainst Predation

o Fleeing or runningFleeing or runningo Mechanical defensesMechanical defenses

• Ex: quills of porcupines, shell of turtlesEx: quills of porcupines, shell of turtleso Living in groupsLiving in groupso CamouflageCamouflageo Chemical defenses- Chemical defenses- poisonspoisons

• Ex: brightly colored poison Ex: brightly colored poison arrow frogarrow frog

CompetitionCompetitiono Interaction among organisms that vie Interaction among organisms that vie

for the same resource in an ecosystemfor the same resource in an ecosystemo IntraspecificIntraspecific

• Competition between individuals in a Competition between individuals in a populationpopulation

o Interspecific Interspecific • Competition between individuals in 2 Competition between individuals in 2

different speciesdifferent species

In-class Discussion In-class Discussion Readers:Readers:

Chapter Chapter ##1 - Me1 - MeChapter Chapter ##2 – 2 – Chapter Chapter ##3 – Elizabeth Goodrich3 – Elizabeth GoodrichChapter Chapter ##4 – James McLeod4 – James McLeodChapter Chapter ##5 – Labecca Hampton and 5 – Labecca Hampton and Jessica VidalJessica VidalChapter Chapter ##6 – Patrick Grennan and 6 – Patrick Grennan and Scott ArnoldScott ArnoldChapter Chapter ##7 – William Arnold and 7 – William Arnold and David DudleyDavid DudleyChapter Chapter ##8 – Crissy Overgard8 – Crissy OvergardChapter Chapter ##9 – Juan Rodriguez9 – Juan Rodriguez

Readings last Week Readings last Week and this Week:and this Week:

Chapter Chapter ##5 – “5 – “Free WealthFree Wealth” ”

Facilitators: Labecca Hampton and Jessica

VidalQuizzes will be returned on Wednesday

Ecological NicheEcological Nicheo The totality of an organisms The totality of an organisms

adaptations, its use of resources, and adaptations, its use of resources, and the lifestyle to which it is fittedthe lifestyle to which it is fitted

o Takes into account all aspect of an Takes into account all aspect of an organisms existenceorganisms existence• Physical, chemical, biological factors Physical, chemical, biological factors

needed to surviveneeded to survive• HabitatHabitat• Abiotic components of the environmentAbiotic components of the environment

• Ex: Light, temperature, moistureEx: Light, temperature, moisture

Ecological NicheEcological Nicheo Fundamental nicheFundamental niche

• Potential idealized ecological niche Potential idealized ecological niche

o Realized nicheRealized niche• The actual niche the organism occupiesThe actual niche the organism occupies

o Ex: Green Anole and Brown AnoleEx: Green Anole and Brown Anole

Ecological NicheEcological Nicheo Green Anole and Brown AnoleGreen Anole and Brown Anole

• Fundamental niches of 2 lizards initially Fundamental niches of 2 lizards initially overlappedoverlapped

• Brown anole eventually out-competed the Brown anole eventually out-competed the green anole- reduced the green anole’s green anole- reduced the green anole’s realized nicherealized niche

Limiting ResourcesLimiting Resourceso Any environmental resource that, because it is Any environmental resource that, because it is

scarce or at unfavorable levels, restricts the scarce or at unfavorable levels, restricts the ecological niche of an organism (ecological niche of an organism (Leibig’s Law of Leibig’s Law of MinimumMinimum))

Interspecific CompetitionInterspecific Competition

Competitive Exclusion & Competitive Exclusion & Resource PartitioningResource Partitioning

o Competitive Exclusion PrincipleCompetitive Exclusion Principle• One species excludes another from a portion of the One species excludes another from a portion of the

same niche as a result of competition for resourcessame niche as a result of competition for resources

o Resource PartitioningResource Partitioning• Coexisting species’ niche differ from each other in Coexisting species’ niche differ from each other in

some waysome way

Keystone SpeciesKeystone Specieso A species that exerts profound A species that exerts profound

influence on a communityinfluence on a community• More important to the community than More important to the community than

what would be expected based on what would be expected based on abundanceabundance

o The dependence of other species on The dependence of other species on the keystone species is apparent when the keystone species is apparent when the keystone species is removedthe keystone species is removed• Protecting keystone species is a goal to Protecting keystone species is a goal to

conservation biologistsconservation biologists

Species RichnessSpecies Richnesso The number of The number of

species in a species in a communitycommunity• Tropical Tropical

rainforests = high rainforests = high species richnessspecies richness

• Isolated island = Isolated island = low species low species richnessrichness

o Related to the Related to the abundance of abundance of potential potential ecological nichesecological niches

Ecosystem ServicesEcosystem Serviceso Important environmental benefits that Important environmental benefits that

ecosystems provide, such as:ecosystems provide, such as:• Clean air to breatheClean air to breathe• Clean water to drinkClean water to drink• Fertile soil in which to grow crops Fertile soil in which to grow crops

Ecosystem ServicesEcosystem Services