Natural selection changes a population over generations
הוצג| English | משמעות |
|---|---|
| evolution/ɪvəˈluːʃn/ | אבולוציה |
| natural selection/ˈnætʃərəl sɪˈlekʃn/ | בחירה טבעית |
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.
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?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Selection works through reproductive success: carriers of the advantageous variant survive and leave more offspring, so the variant becomes commoner each generation. Individuals cannot change their DNA by choice.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
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.
In the lab: 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?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- 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.
Your turn: A model begins with 50 pale beetles and 40 survive. Find pale survival percentage.
A model begins with 50 pale beetles and 40 survive. Find pale survival percentage.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 80 %. Known: 40 of 50 pale beetles survive. Use survival percentage = survivors / initial x 100. Percentage = 40/50 x 100 = 80%. Compare with the other variant using its own denominator.
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.
Not true: Natural selection changes every individual into a new species during its lifetime. Selection changes the POPULATION over generations as variant frequencies shift. No individual transforms into a new species during its lifetime; speciation takes many generations of divergence.
- Evolution is a change in inherited characteristics of a population over time.
- The theory explains living species evolving from simple early life forms over more than three billion years.
- Watch for: fitness means reproductive success in the environment, not physical strength alone.
Natural selection changes every individual into a new species during its lifetime.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Selection changes the POPULATION over generations as variant frequencies shift. No individual transforms into a new species during its lifetime; speciation takes many generations of divergence.
Differential survival and reproduction of inherited variants: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
natural selection means Differential survival and reproduction of inherited variants.