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Lecture 8: Genetics and Humans' Place in Nature - Natural Selection and Population Genetics Lecture 8: Genetics and Humans' Place in Nature - Natural Selection and Population Genetics
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Sign in to readLecture 8: Genetics and Humans’ Place in Nature - Natural Selection and Population Genetics
Important Announcements
Monday October 6 - Recorded Lecture
Week 5 Schedule (Sept. 29-Oct. 3)
Review: Darwin’s Three Postulates
Darwin’s Finches: Natural Selection in Action
Research by Peter and Rosemary Grant
The 1977 Drought Event
Postulate 1: Struggle for Existence
Postulate 2: Variation
Postulate 3: Heritability
Types of Selection: Stabilizing Selection
Selection Is NOT Directional
Individual Selection
Key Principle
Example: Fecundity in Primates
The Evolution of Complex Adaptations
The Challenge
Richard Dawkins’ Weasel Program
Example Trial 1
Key Insight
Selection for Intermediate Steps
Example: Eye Evolution in Mollusks
Convergent Evolution
Definition
Evidence for Natural Selection
Example: Tasmanian Wolf vs. Coyote
Artificial Selection
Human-Directed Evolution
Pigeon Breeding Example
Modern Example: Corn Oil Content
Darwin and Mendel: Reconciling Two Theories
The Apparent Conflict
The Modern Synthesis
Key Figures in Modern Synthesis (1930s-1940s)
Core Definition
EVOLUTION occurs when the ALLELES in a POPULATION CHANGE OVER TIME
Population Genetics Fundamentals
Example: PKU (Phenylketonuria)
How Natural Selection Changes Gene Frequencies
The Genetics of Continuous Variation
From Discrete to Continuous Traits
One Gene, Two Alleles
Two Genes, Each with Two Alleles
Three Genes, Each with Two Alleles
Monogenic vs. Polygenic Traits
Polygenic Trait Example: Height
Midparent Stature Study
Heritability
Key Definitions
Important Points About Heritability
How Variation Is Maintained
Example: Corn Oil Content Selection
Natural Selection and Behavior
Behavioral Flexibility Can Evolve
Example: Soapberry Bug Mate Guarding
Experimental Results
How Does Behavioral Flexibility Evolve?
Constraints on Adaptation
Example: Darwin’s Finch Beak Dimensions
2. Genetic Drift
Definition
How It Works
Types of Genetic Drift
Drift vs. Selection
Forces of Evolution: Summary
1. Natural Selection
2. Mutation
3. Gene Flow
4. Genetic Drift
Connections to Course Themes
Building on Previous Lectures
Preview: Applying These Concepts
Key Takeaways