Download - Foothill High School Science Department Evolution of Populations The Process of Speciation
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Evolution of PopulationsEvolution of Populations
The Process of SpeciationThe Process of Speciation
Foothill High School Science DepartmentFoothill High School Science Department
The Process of SpeciationThe Process of Speciation
• SpeciationSpeciation– The Formation of New SpeciesThe Formation of New Species
• SpeciesSpecies– A Group of Organisms That Breed With A Group of Organisms That Breed With
One Another And Produce Fertile OffspringOne Another And Produce Fertile Offspring– Individuals In The Same Species Share A Individuals In The Same Species Share A
Common Gene PoolCommon Gene Pool
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Isolating MechanismsIsolating Mechanisms
Key ConceptKey Concept:–As New Species Evolve,As New Species Evolve,• Populations Become More Populations Become More
Reproductively Isolated From Reproductively Isolated From Each OtherEach Other
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Isolating MechanismsIsolating Mechanisms
ReproductiveReproductive IsolationIsolation–When Members Of Two Populations When Members Of Two Populations
Cannot Interbreed And Produce Cannot Interbreed And Produce Fertile OffspringFertile Offspring• The Populations Have Separate Gene The Populations Have Separate Gene
PoolsPools
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Reproductive IsolationReproductive Isolation
Can Occur ThroughCan Occur Through:1.1. Behavioral IsolationBehavioral Isolation2.2. Geographic IsolationGeographic Isolation3.3. Temporal IsolationTemporal Isolation
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Behavioral IsolationBehavioral Isolation
Two or More Populations Are Capable of Two or More Populations Are Capable of Interbreeding But Don’t Due To:Interbreeding But Don’t Due To:
• Behavior Differences e.g.Behavior Differences e.g.–Different Courtship RitualsDifferent Courtship Rituals–Other Types of BehaviorOther Types of Behavior• Courtship SongsCourtship Songs• Courtship BehaviorCourtship Behavior• Sleep/Wake Cycles, etc.Sleep/Wake Cycles, etc.
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Easte
rn
Mead
ow
lark
Each Species Has Each Species Has Separate Mating SongSeparate Mating Song
West
ern
M
eadow
lark
Behavioral IsolationBehavioral IsolationPopulations May Share Populations May Share Overlapping TerritoriesOverlapping Territories
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Geographic IsolationGeographic Isolation
Populations Are Separated By Populations Are Separated By Geographic Barriers e.g.Geographic Barriers e.g.
RiversRiversMountainsMountains
Bodies of WaterBodies of WaterDesertsDeserts
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Geographic IsolationGeographic Isolation
• Grand Canyon SquirrelsGrand Canyon Squirrels– Colorado River Formation Of Colorado River Formation Of
The Grand Canyon Separated The Grand Canyon Separated Populations Of Abert Squirrels Populations Of Abert Squirrels About 10,000 Years Ago.About 10,000 Years Ago.
– Separate species – The Kaibab Separate species – The Kaibab Squirrel DevelopedSquirrel Developed
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Kaibab
Abert
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Temporal IsolationTemporal Isolation
Two Or More Species Reproduce At Two Or More Species Reproduce At Separate TimesSeparate Times
–Three species of Orchids Each Release Three species of Orchids Each Release Pollen On Different DaysPollen On Different Days–Frogs in same pond breed in different Frogs in same pond breed in different
monthsmonths
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Testing Natural Selection In NatureTesting Natural Selection In Nature
• Galapagos FinchesGalapagos Finches– Darwin’s Radiation Theory Darwin’s Radiation Theory
Proven By Peter & Proven By Peter & Rosemary Grant of Rosemary Grant of Princeton UniversityPrinceton University
– RequiredRequired• VariationVariation• Beak Size Must Change Beak Size Must Change
FitnessFitness
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Testing Natural Selection In NatureTesting Natural Selection In Nature
Grants Realized Darwin’s Hypothesis Grants Realized Darwin’s Hypothesis Relied On Two Testable Relied On Two Testable
Assumptions:Assumptions:1.1. Inheritable Variation Must Be Present Inheritable Variation Must Be Present
In Current PopulationIn Current Population2.2. Variations Must Produce Enough Variations Must Produce Enough
Differences In Fitness That Natural Differences In Fitness That Natural Selection Will OccurSelection Will Occur
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VariationVariation
On A Single Island The Grant’s Mapped:On A Single Island The Grant’s Mapped:PopulationsPopulations
Breeding SuccessBreeding SuccessWing, Leg, Beak LengthWing, Leg, Beak Length
Beak Depth & ColorBeak Depth & ColorFeather ColorsFeather Colors
Bird MassBird MassThey Verified Genetic VariationThey Verified Genetic Variation
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Natural SelectionNatural Selection
The Grant's studied finches on Daphne Major,The Grant's studied finches on Daphne Major,a small island (800 sq. yd)a small island (800 sq. yd)
In 1977 island had only 2mm of rainIn 1977 island had only 2mm of raininstead of normal 130mm... instead of normal 130mm...
The drought resulted in a loss ofThe drought resulted in a loss of84% of medium ground finch population.84% of medium ground finch population.
Most died of starvation!Most died of starvation!
Foothill High School Science DepartmentFoothill High School Science Department
Foothill High School Science DepartmentFoothill High School Science Department
Rapid EvolutionRapid Evolution
They Were Able To DocumentThey Were Able To DocumentSeveral Incidences of Rapid Several Incidences of Rapid Evolution On Daphne MajorEvolution On Daphne Major
Over Several DecadesOver Several Decades
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Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
Key ConceptKey ConceptSpeciation In The Galapagos Finches Speciation In The Galapagos Finches
Occurred By Founding Of A New Occurred By Founding Of A New Population, Geographic Isolation, Changes Population, Geographic Isolation, Changes In The New Populations Gene Pool, In The New Populations Gene Pool, Reproductive Isolation, And Ecological Reproductive Isolation, And Ecological CompetitionCompetition
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Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
Foothill High School Science DepartmentFoothill High School Science Department
Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
Foothill High School Science DepartmentFoothill High School Science Department
Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
Foothill High School Science DepartmentFoothill High School Science Department
Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
A & B Don’t Mate
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Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches
Foothill High School Science DepartmentFoothill High School Science Department
Speciation In Darwin’s FinchesSpeciation In Darwin’s Finches