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Unit Overview

  • Unit 7: Natural Selection

    • Lesson 1: Natural Selection

    • Lesson 2: Population Genetics

    • Lesson 3: Hardy Weinberg Equilibrium

    • Lesson 4: Evidence of Evolution & Common Ancestry

    • Lesson 5: Phylogeny

    • Lesson 6: Speciation & Extinction

    • Lesson 7: Origins of Life on Earth

Lesson 1: Natural Selection

Aim

  • What causes natural selection and how does it affect populations?

Key Concepts

  1. Variation

    • Genetic variation exists within populations and can be inherited.

  2. Competition

    • Overproduction of offspring leads to competition for resources and survival.

  3. Selection

    • Individuals with beneficial adaptations are more likely to survive and pass on their genes.

    • Over generations, allele frequencies change leading to evolution.

Lesson 2: Population Genetics

Aim

  • What are the different mechanisms of evolution?

Population Genetics Basics

  • Population: A group of individuals of the same species in a specific area that interbreed.

  • Gene Pool: The total genetic diversity within a population which includes all alleles.

  • Allele Frequency Changes: Changes occur due to:

    • Mutations: Source of genetic variation.

    • Genetic Drift: Random changes in allele frequency, especially significant in small populations.

    • Gene Flow: Transfer of alleles due to migration.

    • Natural Selection: Favorable traits increase in frequency.

Lesson 3: Hardy-Weinberg Equilibrium

Aim

  • What is Hardy-Weinberg equilibrium?

Hardy-Weinberg Basics

  • Equilibrium Equation:

    • P + q = 1 (frequency of dominant + recessive alleles)

    • p² + 2pq + q² = 1 (Genotype frequencies)

Conditions for Hardy-Weinberg Equilibrium

  1. No mutations

  2. Random mating (no sexual selection)

  3. No natural selection

  4. No genetic drift

  5. No gene flow

  • Failure to meet conditions results in microevolution.

Lesson 4: Evidence of Evolution & Common Ancestry

Aim

  • What evidence supports evolution and common ancestry?

Types of Evidence

  1. Fossil Record: Visual representation of evolutionary changes over time.

  2. Comparative Morphology: Study of structure similarity across species.

    • Homologous Structures: Similar origins but different functions.

    • Vestigial Structures: Remnants without function (e.g., human appendices).

  3. Biogeography: Species distribution patterns indicate evolutionary relationships.

Lesson 5: Phylogeny

Aim

  • How do phylogenetic trees and cladograms display evolutionary relationships?

Phylogenetic Relationships

  • Systematics: Classification based on evolutionary relationships.

  • Use of fossil records, DNA, and homologous structures to determine relations.

Lesson 6: Speciation & Extinction

Aim

  • What causes new species to arise and what may cause extinction?

Speciation Process

  • Species: Group able to interbreed.

  • Allopatric Speciation: Geographic isolation due to barriers.

  • Sympatric Speciation: New species arise without geographic separation.

Extinction Factors

  • Environmental changes can rapidly increase extinction rates.

Lesson 7: Origins of Life on Earth

Aim

  • What scientific models explain the origin of life?

Hypotheses on the Origin of Life

  1. Miller-Urey Experiment: Demonstrated organic compounds can form under early Earth conditions.

  2. RNA World Hypothesis: Suggests RNA as the first genetic material capable of self-replication.

  3. Evolution of Complex Life: Simple organic molecules combined to form complex structures leading to life.