foothill high school science department evolution of populations evolution as genetic change
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Foothill High School Science DepartmentFoothill High School Science Department
Evolution of PopulationsEvolution of Populations
Evolution As Genetic ChangeEvolution As Genetic Change
Foothill High School Science DepartmentFoothill High School Science Department
Natural SelectionNatural Selection
Does NOTNOT Act Directly On GenesDoes Act On PhenotypesPhenotypes
The Phenotype Gives The Survival Edge
But, In Order To Modify the Gene Pool:But, In Order To Modify the Gene Pool:Survivors Must ReproduceSurvivors Must Reproduce
Alters Relative FrequencyAlters Relative Frequencyof Alleles Over Timeof Alleles Over Time
Foothill High School Science DepartmentFoothill High School Science Department
EvolutionEvolution
Acts On PopulationsActs On Populations
EvolutionDoes NOTNOT ActOn Individuals
Foothill High School Science DepartmentFoothill High School Science Department
Natural Selection on Single Gene TraitsNatural Selection on Single Gene Traits
Key ConceptKey Concept
Natural SelectionNatural SelectionOn Single-Gene TraitsOn Single-Gene TraitsCan Lead To ChangesCan Lead To ChangesIn Allele FrequenciesIn Allele Frequencies
And Thus To EvolutionAnd Thus To Evolution
Foothill High School Science DepartmentFoothill High School Science Department
CamouflageCamouflage
Foothill High School Science DepartmentFoothill High School Science Department
CamouflageCamouflage
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CamouflageCamouflage
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Natural Selection on Single Gene TraitsNatural Selection on Single Gene Traits
BUT:What If Black Allowed The Lizard To
Warm Up Faster & Move Quicker??????
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Natural Selection on Polygenic TraitsNatural Selection on Polygenic Traits
• Traits Controlled By More Than One Gene–Effects On Natural Selection Are More
Complex
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Natural Selection on Polygenic TraitsNatural Selection on Polygenic Traits
Key ConceptKey ConceptNatural Selection Can Affect The
Distribution Of Phenotypes In Any Of Three Ways:1.1. Directional SelectionDirectional Selection2.2. Stabilizing SelectionStabilizing Selection3.3. Disruptive SelectionDisruptive Selection
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Directional SelectionDirectional Selection
• Individuals At One End Of The Standard Curve Have Higher Fitness Than Individuals In The Middle, Or At The Other End–Curve Moves, Over Time, Toward The Curve Moves, Over Time, Toward The
End With Increased FitnessEnd With Increased Fitness
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Directional SelectionDirectional Selection
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Stabilizing SelectionStabilizing Selection
When Individuals NearThe CenterCenter Of The Standard Curve Have
Higher FitnessHigher FitnessThan Individuals On Either End
May Narrow The CurveExample: Human Birth Weight
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Stabilizing SelectionStabilizing Selection
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Disruptive SelectionDisruptive Selection
When Individuals At TheUpper And The Lower EndUpper And The Lower End
Have Higher FitnessHigher Fitness Than Individuals Near The Middle.
If Severe Enough, May Cause The Development If Severe Enough, May Cause The Development Of TWO PhenotypesOf TWO Phenotypes
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Disruptive SelectionDisruptive Selection