As a high school or undergraduate, Biological Sciences teacher, you can use this set of computer-based tools to teach about natural selection, its role in evolution and climate change as a selective pressure in natural selection.
This lesson plan will enable the students to understand Darwin’s theory of natural selection. They will learn how organisms such as pocket mice and Snowshoe hares respond to changes in the environment and climate. The lesson plan will allow students to understand climate change as a selective pressure in natural selection and how it plays a role in the evolutionary rescue of a species that would otherwise be endangered due to climate change.
Thus, the use of this lesson plan allows you to integrate the teaching of a climate science topic with a core topic in the Biological Sciences.
Teacher- contributed lesson plan by Dr Jaspreet Kaur, Maitreyi College and Dr Simran Jit, Miranda House, (University of Delhi), India.
Want to know more about how to contribute? Contact us.
About Lesson Plan
|Grade Level||High school, Undergraduate|
|Topic(s) in Discipline||
|Climate Topic||Climate and the Biosphere|
Use this lesson plan to help your students find answers to:.
- What is Darwin’s theory of natural selection? Illustrate this with an example.
- What is genetic polymorphism?
- Why is genetic variation critical to the survival of a species?
- What is selective pressure?
- How does it affect allelic frequencies in successive generations of a population of organisms?
|An in-chapter reading that briefly introduces Darwin’s theory of natural selection.
Go to the Reading
|An interactive video to illustrate Darwin’s theory of natural selection. It uses the example of fur coat colour in pocket mice.|
|Video and associated reading
|A video and associated reading that shows that climate change can be a selective pressure in natural selection. It uses the example of coat colour in the Snowshoe hare populations in North America.|
|An optional computer lab-based simulation activity to illustrate the changes in single gene allelic frequencies under a varying selective pressure.|
Here is a step-by-step guide to using this lesson plan in the classroom/laboratory. We have suggested these steps as a possible plan of action. You may customize the lesson plan according to your preferences and requirements.
Step 1: Topic introduction and discussion (Reading)
- Use the in-chapter reading, “Major Themes in Evolution”, from the National Academies Press (Chapter 3, pgs 11-16) to introduce the topic of natural selection.
- Use this resource to explain how Darwin and Wallace proposed the theory of natural selection on variants within a species that explained the process of evolution.
- Also explain how Mendel’s work explained how favored characteristics are inherited and eventually lead to speciation.
- Go to the Reading
Step 2: Illustrate the theory with an example (Interactive video)
- Use this interactive resource titled “The Making of the Fittest: Natural Selection and Adaptation” by Howard Hughes Medical Institute to illustrate an example of natural selection.
- Explain how a selection pressure of dark coloured surfaces on light coloured pocket mice has resulted in a natural selection for darker coloured pocket mice that are better camouflaged against predators.
- Use the questions from this resource to quiz students on their understanding of the theory of natural selection when a selective pressure is in play.
- Go to the Video
Step 3: Correlate this understanding to a climate related example of natural selection in another species (video and associated reading)
- Play the video, “Will Snowshoe Hares Win the Race between Evolution and Climate Change”, by National Geographic to explain how reduced snowfall due to a warming climate, behaves as a selective pressure on the seasonal coat colour polymorphism of the Snowshoe hares in North America.
- Snowshoe hares change coat colour in different seasons- white when the ground is snow covered and brown when it is not-to protect themselves from predators. Use the resource to stress that that snowshoe hares from areas where the ground is snow-covered or from areas where the ground is rarely covered with snow through the year, show no seasonal change in coat colour.
- Emphasize that the areas in between these regions are where most hares that seasonally change their coat colour can be found.
- Use the associated reading, “Mills Lab publishes new article in Science: Research identifies areas where evolution could rescue animals threatened by climate change” by the Mills Lab, University of Montana, to show that research on the Snowshoe hares has established that these intermediary zones are evolutionary hotspots that show a higher percentage of non- colour changing brown snowshoe hares due to the ground remaining snow free for longer as a result of a warming climate.
- Explain how this is an example of ‘evolutionary rescue’ of a species by selection for a character that affords better protection from predators in a changing environment, in this case, due to climate change.
- Go to the Video
- Go to the associated reading
Step 4: Extend this thinking by using this simulation (optional)
- This activity can be conducted, if the teacher wishes to extend the students’ understanding of natural selection by their observations of changes in allelic frequencies over successive generations, due to an adaptive advantage for varying selective pressures.
- Use the simulation, “Natural Selection” by McGraw-Hill Education, to explain to students how the allelic frequencies for a single gene, that codes for body colour, changes through several generations when a varying selection pressure (different environments) is applied.
- Launch the simulation and follow the instructions to run it.
- Select an initial allelic frequency for alleles ‘A’ and ‘a’ of a gene for body colour in a starter population of insects, for a given
- Click the ‘Natural Selection’ tab and then the ‘Generation’ button, in order from G1 to G5.
- Record the data generated in table for changes in allelic frequencies over five generations.
- Use the ‘Reset’ button and repeat this activity for different allelic frequencies of the starter population for a varying environment.
- End-point allelic frequencies can also be compared by varying the allelic frequencies at the start for a given environment.
- The students can then plot graphs depicting the changes in allele frequencies through the generations.
- Students can also use the worksheet to record their observations and fill in answers to the journal questions to provide explanations for their observations.
- This exercise will enable students to observe the changes in allelic frequencies over successive generations. They will be able to understand that if an allele is associated with an adaptive advantage, its frequency will increase in a population and may eventually get fixed while an allele that does not have an advantageous adaptive trait, will decrease in frequency and may eventually be lost from the population.
- Finally, extend their thinking by discussing with the students how a climate related change in environment could play a role in changing the allelic frequencies for the given gene.
- Go to the Activity