Natural Selection

Contributor
PhET™ interactive Science Simulations
Type Category
Instructional Materials
Types
Simulation
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

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3 (1 reviews)

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Most Recent Review

4 eye opener

The only reason it’s not 5 stars is because I had to change from winter to summer. If there was a season setting to show how the rabbit’s fur aided in its survival. I ran the simulations for about 3 min without saying a word. When students would ask me question I would just say let’s see what happens. By the end of the demo, they were eager to learn.

Description

This interactive simulation allows students to explore natural selection in bunnies by controlling factors in the environment (equator or arctic environment), selection factors (wolves, food), and characteristics of the bunnies (fur color, tail length and teeth length). The bunnies in the default setting in the simulation have white fur, short tail, and short teeth. There is an option to introduce mutations, which causes bunnies with brown fur, long tail, or long teeth to appear. The user can also edit genes (select whether the mutation for fur color, tail length and teeth length is dominant or recessive). The simulation output includes a chart with the population of bunnies (number of bunnies) on the y-axis, plotted against time on the x-axis. There is an option to see a pedigree when the user clicks on an individual bunny moving within the environment (equator or arctic). Students can make predictions and/or ask questions prior to running the simulation. They can run the simulation, controlling and changing variables, and analyze the data generated by the simulation (output graph). The simulation itself does not come with instructions or a lesson plan. However, there are several lesson plans posted on the website. These lesson plans are from authors independent of the authors of the simulation. This review is limited to reviewing the PHET natural selection simulation, and not any of the lesson plans from outside authors.

Intended Audience

Learner
Educational Level
  • High School
Language
English
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-LS4-2 Construct an explanation based on evidence that the process of evolution primarily results from four factors: (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.

Clarification Statement: Emphasis is on using evidence to explain the influence each of the four factors has on number of organisms, behaviors, morphology, or physiology in terms of ability to compete for limited resources and subsequent survival of individuals and adaptation of species. Examples of evidence could include mathematical models such as simple distribution graphs and proportional reasoning.

Assessment Boundary: Assessment does not include other mechanisms of evolution, such as genetic drift, gene flow through migration, and co-evolution.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This simulation gives students an opportunity to observe and describe how the increase in number of bunnies (“add a friend” in the simulation starts the bunnies reproducing), genetic variation of individual bunnies (click on mutation in the simulation and then observe the phenotype of the bunnies populating the environment), competition for food and predation by wolves leads to the proliferation of those bunnies that are better able to survive in the environment. Teachers should embed this simulation into their instructional sequence where they feel it best fits. Teacher questioning and support of students is dependent on student background knowledge of the concept and their familiarity with simulations. Students should be working on this simulation with a partner, so they have the opportunity to discuss what they are observing, what questions they could be investigating with this simulation, how to display and analyze data, and how to write an evidence-based explanation answering their questions. Teachers should monitor for student understanding throughout the activity, and use some form of large-group share-out to make sure that all students are making progress toward the performance expectation. Depending on where in the unit teachers are when using this simulation, the following directions and prompts can be helpful in supporting students to make progress toward meeting the Performance Expectation. These questions/prompts are adapted from a related resource “Quakers and Cottontails” https://www.nms.org/Portals/0/Docs/FreeLessons/BIO_Quackers%20and%20Cottontails_web.pdf. “Quakers and Cottontails” is published by the National Math and Science Initiative (NMSI). The Cottontail portion uses the PHET simulations. (If teachers are using the Quaker portion of the NMSI lesson plan as well, it is important to discuss the limitation of the Quaker simulation, so students do not walk away with misconceptions). Introduction to the Simulation • What variables are you able to manipulate in this simulation? • Start the simulation by clicking the “PLAY” button. What happens if you never “add a friend?? Explain • Add a friend. Let the simulation continue to run until it stops, and then discuss what happens. Explain what “selection” factors were lacking for this to occur. • What happens to the population sizes of the two phenotypes after several more generations? Explain why you think this occurred? Using the Simulation to Investigate Natural Selection • The teacher can provide a question for the students to investigate, or students can develop their own question. An example question to investigate with the simulation found in the Cottontail lesson plan is: “A population of short-toothed and long-toothed bunnies is living in the Arctic. Due to harsh conditions food becomes limited. What happens to the population sizes of both phenotypes over the next 10 generations? “ • Teacher should encourage students to plan their investigation (think about how to run the simulation, so that they can collect data that answers their question), create a data table to keep track of the number of individual bunnies with the two phenotypes in each generation, and graph their data for an additional visual representation. • Based on this evidence, students should write and share an evidence-based explanation that answers their question. • Teachers should make sure to include a discussion on the limitations of the simulation in comparison of what might happen in the real world when students share their evidence-based explanations.

Science and Engineering Practices

This resource appears to be designed to build towards this science and engineering practice, though the resource developer has not explicitly stated so.

Comments about Including the Science and Engineering Practice
While students have not developed the model underlying the simulation, they can use it to investigate factors (the potential for a species to increase in number, the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, competition for limited resources, and the proliferation of those organisms that are better able to survive and reproduce in the environment) that influence the process of evolution. Students often struggle with distinguishing what happens to the individual as opposed to the population over time when studying natural selection. This simulation gives students the opportunity to see what happens to the phenotypes of bunnies over several generations when manipulating selection factors. Teachers should explicitly probe for students’ understanding of this aspect during instruction.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
This simulation provides students with the opportunity to manipulate and explore the interaction of factors leading to evolution, and observe how natural selection leads to adaptation, i.e. a population of bunnies suited to survive and reproduce in the environment that students selected by manipulating the settings. Teachers should make sure that students do not just “play” with the simulation, or just “observe” what happens. Instead, after students describe what is happening to the populations of bunnies as they run different trials with different settings, teachers should ask what that means, and ask students to collaboratively develop and defend an explanations based on evidence they collected when running the simulation. Teachers should keep in mind that simulations have benefits and limitations, and that is that important to not exclusively teach natural selection through simulation, but also use data sets from field work, or other real-life demonstrations. The simulation provides students with the opportunity to visually observe how for example, changing the environment (arctic vs. equator) over time leads to a population dominated by bunnies that are well suited to survive in that environment. This illustrates for students that the differential survival and reproduction of bunnies in a population that are better camouflaged leads to an increase in the proportion of these bunnies in future generations and to a decrease in the proportion of bunnies that are not well camouflaged.

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
This simulation provides students with the opportunity to manipulate and explore the interaction of factors leading to evolution, and observe how natural selection leads to adaptation, an example of a cause and effect relationship. The teacher should use questioning strategies to help students understand cause and effect relationships within this simulation. For example students should articulate that when a mutation occurs that provides individual bunnies with the advantage to blend into the background, they are more likely to not be eaten by the wolves, survive and reproduce, which over many generations leads to a higher proportion of bunnies with a fur color that blends into the background.

Resource Quality

  • Alignment to the Dimensions of the NGSS: Elements of the disciplinary core idea are significantly addressed. Use of the simulation provides opportunities to address the practices of using a model, planning and carrying out investigations, and analyzing and interpreting data, as well as describing the cause and effect relationships that are part of the mechanisms of natural selection. All of these connections require that the teacher purposefully facilitates students’ use of the simulation, so that students make meaning of what they are observing.

  • Instructional Supports: This simulation supports instruction and learning for all students by providing students with the opportunity to control a simulation that models a real world scenario of bunnies with different physical characteristics surviving in different environments. As students are making sense of the phenomenon (proportion of different bunnies changing, depending on the variable in the simulations that students change), they are engaged in several practices as well as the crosscutting concept of cause and effect, as they are building their understanding of the disciplinary core idea. The simulation builds on students’ prior knowledge, as most students should be familiar with animals blending into the background to avoid being eaten by predators (wolves in this simulation). Teachers should spend considerable time working with the simulation prior to teaching students. Many aspects of the simulation are not explained or intuitive and there is no guidance for the teacher on how to support students. Teachers need to select appropriate pedagogical strategies from their own repertoire to encourage students to express their thinking and present their ideas to others for peer and teacher feedback as they are working through the simulation. No guidance for differential instruction is provided by the resource.

  • Monitoring Student Progress: The simulation does not provide a method for monitoring student progress. However, the teacher could easily implement the simulation in a way to monitor students’ progress. For example, pairs of students could prepare a presentation that includes the question they investigated, the evidence they collected when they ran the simulation, and their evidence-based explanation answering the question they asked. The teacher could also use the simulation with the whole group and ask questions to check for understanding.

  • Quality of Technological Interactivity: The simulation is straightforward to use and provides numerous ways for students to manipulate it. The functionality is directly related to learning about natural selection. However, there is no explanation with the simulation and the components are not labeled clearly and intuitively.