Natural selection changes a population over generations
| English | 中文 | Pinyin |
|---|---|---|
| evolution/ɪvəˈluːʃn/ | 进化 | jìn huà |
| natural selection/ˈnætʃərəl sɪˈlekʃn/ | 自然选择 | zì rán xuǎn zé |
What would explain this observation?
- A dark beetle does not become light because a habitat becomes pale. Selection changes which inherited variants leave more offspring.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Evolution 进化 is a change in inherited characteristics of a population over time. In natural selection 自然选择, individuals vary and some phenotypes are better suited to their environment. Those individuals are more likely to survive and reproduce successfully. They pass the associated inherited characteristics to offspring, so the relevant variants become more common over generations.
- natural selection: Differential survival and reproduction of inherited variants; evolution: Change in inherited population characteristics over generations.
What directly increases an advantageous inherited variant over generations?
The theory explains living species evolving from simple early life forms over more than three billion years. Selection acts on an existing population with variation; it does not mean every individual changes during its lifetime. If two populations become sufficiently different that they cannot interbreed to produce fertile offspring, they form separate species in the specified model.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- The theory explains living species evolving from simple early life forms over more than three billion years. Selection acts on an existing population with variation; it does not mean every individual changes during its lifetime. If two populations become sufficiently different that they cannot interbreed to produce fertile offspring, they form separate species in the specified model.
- Use a paper population with stated inherited colours and a changing background. Count each variant before and after a simulated selection event, then represent reproduction by survivors. Explain the model’s limitations: real survival has many causes, and changing frequency in one round is evidence of selection rather than proof of a new species.
Which two habits make the investigation or model in this case more defensible?
Use a paper population with stated inherited colours and a changing background. Count each variant before and after a simulated selection event, then represent reproduction by survivors. Explain the model’s limitations: real survival has many causes, and changing frequency in one round is evidence of selection rather than proof of a new species.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a population begins with 20 dark and 80 pale model beetles. After selection, 10 dark and 70 pale remain. Pale survivor fraction = 70/80 = 87.5%, compared with 10/20 = 50% for dark beetles. Pale frequency among survivors is 70/80 = 87.5%; the same number here arises from different denominators, which must be identified.
A model begins with 50 pale beetles and 40 survive. Find pale survival percentage. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A model begins with 50 pale beetles and 40 survive. Find pale survival percentage.
The result is 80 %. Known: a population begins with 20 dark and 80 pale model beetles. After selection, 10 dark and 70 pale remain. Pale survivor fraction = 70/80 = 87.5%, compared with 10/20 = 50% for dark beetles. Pale frequency among survivors is 70/80 = 87.5%; the same number here arises from different denominators, which must be identified.
Check the conclusion and its limits
- Fitness means reproductive success in the environment, not physical strength alone. Individuals do not choose beneficial inherited changes. A new species requires evidence about interbreeding and fertile offspring, not only a difference in appearance.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Natural selection changes every individual into a new species during its lifetime. This claim is false: Fitness means reproductive success in the environment, not physical strength alone. Individuals do not choose beneficial inherited changes. A new species requires evidence about interbreeding and fertile offspring, not only a difference in appearance.
Natural selection changes a population over generations: The theory explains living species evolving from simple early life forms over more than three billion years. Selection acts on an existing population with variation; it does not mean every individual changes during its lifetime. If two populations become sufficiently different that they cannot interbreed to produce fertile offspring, they form separate species in the specified model.
Natural selection changes every individual into a new species during its lifetime.
Fitness means reproductive success in the environment, not physical strength alone. Individuals do not choose beneficial inherited changes. A new species requires evidence about interbreeding and fertile offspring, not only a difference in appearance.
Differential survival and reproduction of inherited variants: write the technical term.
natural selection means Differential survival and reproduction of inherited variants.