View
32
Download
3
Category
Tags:
Preview:
DESCRIPTION
Evolution of Populations. Other Mechanisms of Genetic Change. Gene Flow. Movement of Alleles From One Population To Another Increases Genetic Variation Of The Receiving Population Less Gene Flow – More Differences Between Populations - PowerPoint PPT Presentation
Citation preview
Foothill High School Science DepartmentFoothill High School Science Department
Evolution of PopulationsEvolution of Populations
Other Mechanisms of Genetic ChangeOther Mechanisms of Genetic Change
Foothill High School Science DepartmentFoothill High School Science Department
Gene FlowGene Flow
Movement of Movement of AllelesAlleles
From One PopulationFrom One Population
To AnotherTo Another• Increases Genetic Variation Of The Receiving Increases Genetic Variation Of The Receiving
PopulationPopulation• Less Gene Flow – More Differences Between Less Gene Flow – More Differences Between
PopulationsPopulations– Increases Probability of Each Population Increases Probability of Each Population
Becoming Separate Species.Becoming Separate Species.
Foothill High School Science DepartmentFoothill High School Science Department
Genetic DriftGenetic Drift
• Natural Selection Is Not The Only Natural Selection Is Not The Only Source of Evolutionary ChangeSource of Evolutionary Change
• InIn Small PopulationsSmall Populations– An Allele Can Become More Or Less An Allele Can Become More Or Less
Common Common By ChanceBy Chance
Foothill High School Science DepartmentFoothill High School Science Department
Genetic DriftGenetic Drift
• Smaller Populations Smaller Populations – Can Have Shifts In The Relative Frequency Can Have Shifts In The Relative Frequency
Of Alleles Much Faster Than Larger Of Alleles Much Faster Than Larger PopulationsPopulations
– Their Gene Pool Is SmallerTheir Gene Pool Is Smaller
Genetic DriftGenetic Drift IsIs
The Random ChangeThe Random Change
In Allele FrequencyIn Allele Frequency
Foothill High School Science DepartmentFoothill High School Science Department
Genetic DriftGenetic Drift
Key ConceptKey Concept:In Small Populations, In Small Populations,
Individuals That Carry A Particular Allele Individuals That Carry A Particular Allele May Leave More Descendents Than Other May Leave More Descendents Than Other Individuals, Just By Chance. Individuals, Just By Chance.
Over Time, A Series Of Chance Occurrences Over Time, A Series Of Chance Occurrences Of This Type Can Cause An Allele To Of This Type Can Cause An Allele To Become Common In A PopulationBecome Common In A Population
Foothill High School Science DepartmentFoothill High School Science Department
Genetic DriftGenetic Drift
• Circumstances That May Result In Circumstances That May Result In Genetic Drift:Genetic Drift:
–Founder EffectFounder Effect• Colonization Of A New Habitat By A Colonization Of A New Habitat By A
Small Number of IndividualsSmall Number of Individuals–Hawaiian Fruit FliesHawaiian Fruit Flies–Darwin’s FinchesDarwin’s Finches–Hawaiian Honey CreepersHawaiian Honey Creepers
Foothill High School Science DepartmentFoothill High School Science Department
Founder EffectFounder Effect
Foothill High School Science DepartmentFoothill High School Science Department
Genetic DriftGenetic Drift
The Bottleneck EffectThe Bottleneck Effect• Occurs When Man Made, or Natural Occurs When Man Made, or Natural
Disasters Destroy Most Of A Disasters Destroy Most Of A Population.Population.
• The Remaining Members Usually The Remaining Members Usually Possess A Severely Diminished Possess A Severely Diminished Gene PoolGene Pool
Foothill High School Science DepartmentFoothill High School Science Department
Hardy-Weinberg Principle (1908)Hardy-Weinberg Principle (1908)
Key ConceptKey Concept:Five Conditions Are Required To Maintain Five Conditions Are Required To Maintain
Genetic Equilibrium From Generation To Genetic Equilibrium From Generation To Generation:Generation:
1.1. There Must Be Random MatingThere Must Be Random Mating2.2. The Population Must Be Very LargeThe Population Must Be Very Large3.3. There Can Be No Movement In or Out Of There Can Be No Movement In or Out Of
The PopulationThe Population4.4. No MutationsNo Mutations5.5. No Natural SelectionNo Natural Selection
Foothill High School Science DepartmentFoothill High School Science Department
Random MatingRandom Mating
All Members Of The All Members Of The PopulationPopulation
Must have An Equal Must have An Equal OpportunityOpportunity
To Produce OffspringTo Produce Offspring
Foothill High School Science DepartmentFoothill High School Science Department
Large PopulationLarge Population
Genetic DriftGenetic DriftHas Less EffectHas Less Effect
On Large PopulationsOn Large Populations
Foothill High School Science DepartmentFoothill High School Science Department
No Movement Into or Out Of The PopulationNo Movement Into or Out Of The Population
• New Alleles Must Not EnterNew Alleles Must Not Enter
• Rare Alleles Must NotRare Alleles Must NotBe Allowed To LeaveBe Allowed To Leave
Foothill High School Science DepartmentFoothill High School Science Department
No MutationsNo Mutations
Mutations Introduce New Mutations Introduce New Alleles Causing A Change InAlleles Causing A Change In
Allele FrequenciesAllele Frequencies
Foothill High School Science DepartmentFoothill High School Science Department
No Natural SelectionNo Natural Selection
All GenotypesAll GenotypesMust Have Equal OpportunityMust Have Equal Opportunity
To Survive & ReproduceTo Survive & Reproduce
No PhenotypeNo PhenotypeCan Have An AdvantageCan Have An Advantage
Over AnotherOver Another
Recommended