Natural Selection
Sections
1. Introduction
2. Mouse Simulation Intro
3. Natural Selection
4. Natural Selection Quiz
5. Fish Simulation Intro
6. Ecological Selection
7. Ecological Selection Quiz
Sections
1. Introduction
2. Mouse Simulation Intro
3. Natural Selection
4. Natural Selection Quiz
5. Fish Simulation Intro
6. Ecological Selection
7. Ecological Selection Quiz
1. Introduction
Goals Answer all questions
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| Natural selection is a fundamental mechanism of evolution that describes how traits become more or less common within a population.
Variations in traits arise naturally through gene mutations. Some mutations allow individuals of a population to perform better in their environment, live longer, and have more opportunity to pass on their genes. As those individuals breed, their traits become more common within the population. These traits are said to be naturally selected for. Similarly, variations that have a negative effect and become less common in the population by this mechanism are said to be naturally selected against. Ancestors of the modern horse were smaller and had toes.
Toes allowed these animals to maintain better balance on soft forest floors.
However, as horses began occupying hard, flat plains, having a larger central toe (which eventually evolved into a hoof) yielded better support and faster running speeds.
In this example, larger, faster horses were better suited to outrun plains predators, so hooves and larger size traits were naturally selected for. Conversely, toed horses and horses with shorter legs were not as well equipped to outrun plains predators, so those traits were naturally selected against. Did horses decide to grow longer legs so they could outrun predators?
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2. Mouse Simulation Intro
In the next simulation, you will see mice being naturally selected, depending on their environment.
A mouse with fur that matches its environment is better hidden from predators and therefore more likely to survive and pass on its genes. Conversely, mice that are not camouflaged are more likely to be caught by predators and not pass on their genes.
With each generation, camouflaged mice survive longer and have more opportunity to grow their population.
Non-camouflaged mice are naturally selected against and their populations decline.
A mouse with fur that matches its environment is better hidden from predators and therefore more likely to survive and pass on its genes. Conversely, mice that are not camouflaged are more likely to be caught by predators and not pass on their genes.
With each generation, camouflaged mice survive longer and have more opportunity to grow their population.
Non-camouflaged mice are naturally selected against and their populations decline.
3. Natural Selection
Instructions Click Start to run the simulation of mouse populations. Allow brown mice to become at least 75% of the population. Then change the environment to allow gray mice to dominate at least 75%. Do the same for white mice. If one of the types of mice reaches 0, you can click reset to return to the starting populations. Goals Achieve >75% brown mice.
Achieve >75% gray mice.
Achieve >75% white mice.
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4. Natural Selection Quiz
Goals Answer all questions
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| A region with a large, steady population of white mice suggests which of the following?
A significant sample of mice from a field contains equal amounts of brown and gray mice. Which of the following would be a good hypothesis to explain this scenario? Which of the following is correct? Mice develop fur colors to match their environments. Field predators only eat grey or white mice, not brown mice. |
5. Fish Simulation Intro
Natural selection is an ongoing, dynamic process.
Traits that were beneficial in past generations may not be beneficial in future generations.
In this freshwater lake there are two variations of a fish species: blue fish and brown fish.
When the lake is clean, the blue fish will not be as easily spotted by predators, so the blue trait will be selected for. If the water becomes polluted, the brown fish will become better camouflaged so their numbers may increase. If pollution is cleaned up, the blue fish may become less visible to predators again.
In this freshwater lake there are two variations of a fish species: blue fish and brown fish.
When the lake is clean, the blue fish will not be as easily spotted by predators, so the blue trait will be selected for. If the water becomes polluted, the brown fish will become better camouflaged so their numbers may increase. If pollution is cleaned up, the blue fish may become less visible to predators again.
6. Ecological Selection
7. Ecological Selection Quiz
Goals Answer all questions
Submit your answers
| Which of the following is true?
If a clean lake has a much larger population of brown fish than blue fish, which of the following could be true? If the lake has equal populations of blue and brown fish, which of the following could be true? If a population of blue fish is in decline, it will always recover as soon as the pollution is cleaned up. In the real world, even after all the brown fish in a clean lake have been eaten by predators, there may still be more brown fish in later generations. |
8. Lesson Done
Instructions You have completed the lesson. You may scroll up to review the lesson. |
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