Genetic Variation and the Origin of Species

Biology Grades High School 11:52 Video
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Lesson Description

Explore the relationship between genes, genetic variation, and the formation of new species. Learn about DNA, mutations, gene flow, and the role of natural selection in shaping biodiversity.

Video Resource

Genetic variation, gene flow, and new species

California Academy of Sciences

Duration: 11:52
Watch on YouTube

Key Concepts

  • DNA structure and function
  • Mutations and genetic variation
  • Gene flow and reproductive isolation
  • Natural selection and adaptation
  • Speciation

Learning Objectives

  • Students will be able to describe the structure and function of DNA.
  • Students will be able to explain how mutations and sexual reproduction create genetic variation.
  • Students will be able to define gene flow and explain its role in maintaining species consistency.
  • Students will be able to explain how reproductive isolation can lead to speciation.
  • Students will be able to describe the role of natural selection in adaptation and evolution.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they know about DNA and evolution. Briefly introduce the video and its main topics: genetic variation, gene flow, and speciation.
  • Video Viewing (15 mins)
    Play the YouTube video "Genetic variation, gene flow, and new species" by the California Academy of Sciences. Encourage students to take notes on key concepts.
  • Discussion (15 mins)
    Facilitate a class discussion based on the video content. Use the discussion questions provided to guide the conversation.
  • Interactive Exercise: Modeling Speciation (20 mins)
    Have students participate in the modeling exercise (see interactive exercises section).
  • Wrap-up and Assessment (5 mins)
    Summarize the key concepts covered in the lesson. Assign the multiple-choice and fill-in-the-blank quizzes as a formative assessment.

Interactive Exercises

  • Modeling Speciation
    Divide students into small groups. Each group represents a population of organisms. Give each group a set of beads representing different alleles for a specific trait (e.g., beak size in birds). Initially, all groups have similar allele frequencies. Introduce a barrier (e.g., a table dividing the group) to simulate geographic isolation. Instruct each group to randomly select beads (alleles) for the next generation, with a slight bias towards alleles that confer an advantage in their 'environment' (e.g., larger beaks if the available food is harder to crack). After several 'generations,' compare the allele frequencies in each group. Discuss how the isolated populations have diverged genetically and phenotypically due to the barrier and differing selective pressures.

Discussion Questions

  • What is DNA and how does it function as the genetic code?
  • How do mutations contribute to genetic variation?
  • What is gene flow and how does it affect the genetic makeup of a population?
  • Explain how reproductive isolation can lead to the formation of new species.
  • What role does natural selection play in the process of evolution?

Skills Developed

  • Critical thinking
  • Data Interpretation
  • Scientific communication
  • Modeling
  • Analyzing

Multiple Choice Questions

Question 1:

What is the function of DNA?

Correct Answer: To store and transmit genetic information

Question 2:

What are mutations?

Correct Answer: Changes in the sequence of nucleotides in DNA

Question 3:

What is gene flow?

Correct Answer: The movement of genes between populations

Question 4:

What is reproductive isolation?

Correct Answer: The inability of two populations to interbreed and produce fertile offspring

Question 5:

What is speciation?

Correct Answer: The formation of new species

Question 6:

What are different forms of the same gene called?

Correct Answer: Alleles

Question 7:

Approximately how much DNA is in each human cell?

Correct Answer: 2-3 meters

Question 8:

What can cause mutations?

Correct Answer: Mistakes in DNA replication

Question 9:

What is the Isthmus of Panama an example of?

Correct Answer: A geographic barrier

Question 10:

How does evolution occur?

Correct Answer: Randomly by mutation and recombination

Fill in the Blank Questions

Question 1:

The sequences of ________ spell out codes that give orders to the cellular machinery to make the cell work.

Correct Answer: nucleotides

Question 2:

The number of ________ varies from species to species.

Correct Answer: chromosomes

Question 3:

Changes in the sequence of letters in the words that make up the genetic code are called ________.

Correct Answer: mutations

Question 4:

During sexual reproduction, a huge amount of genetic ________ occurs, a kind of reshuffling of the genetic deck.

Correct Answer: recombination

Question 5:

The mixing of genetic information among interbreeding members of a population is known as ________.

Correct Answer: gene flow

Question 6:

The backbone of DNA is made of special sugar molecules called ________.

Correct Answer: deoxyribose

Question 7:

________ is the splitting of a single species into two descendant species.

Correct Answer: speciation

Question 8:

The differing environmental conditions in isolated groups causes different ________ forces.

Correct Answer: selection

Question 9:

Mutations result in different forms of the same gene. These different forms are called ________.

Correct Answer: alleles

Question 10:

Pairs of species that are closely related and on different sides of a geographic barrier are called ________ species.

Correct Answer: geminate

Educational Standards

B.LS3.1:Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. B.LS3.2:Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors. B.LS4.2:Construct an explanation based on evidence that biological diversity is influenced by (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment. B.LS4.5:Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

Teaching Materials

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