Evolutionary evidence: independent lines support an explanation
導入済み| English | 意味 |
|---|---|
| inherited variant/ɪnˈherɪtɪd ˈveərɪənt/ | 遺伝的変異型 |
| fossil record/ˈfɒsl ˈrekɔːd/ | 化石記録 |
What would explain this observation?
- A fossil series and a changing bacterial population provide different kinds of evidence. Their value is stronger when they support the same causal account.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Evolution by natural selection is widely accepted because evidence has accumulated. Genetics shows inherited characteristics can pass to offspring through genes. Fossils show organisms and patterns of change through time. Bacterial populations demonstrate that resistant inherited variants 遗传变异型 can survive selection and become more common as susceptible bacteria are removed.
- fossil record 化石记录: The available fossil evidence of past organisms; inherited variant: A genetic form that can pass to later generations.
Which is evidence of population evolution under selection?
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Evolution is a population-level change: an inherited resistant variant becoming commoner over generations is direct evidence of it. Individuals choosing resistance, or changing size in a meal, is not evolution.
Match each technical term to its precise meaning.
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Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Each line answers a different question. A fossil gives evidence of past organisms but usually cannot show their complete DNA. A resistance dataset can show population change over generations but is not a complete history of all life. Agreement between inheritance mechanisms, historical records and observed selection strengthens the explanation.
- For each supplied dataset, write observation → supported inference → limitation. Compare relative ages of fossils with a labelled evolutionary tree and inspect bacterial counts before and after a stated treatment. Use prepared records only; evolving antibiotic resistance by culturing organisms is not a classroom activity.
Which two habits make the investigation or model in this case more defensible?
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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
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a fictional bacterial sample contains 5 resistant cells out of 100 before selection and 20 out of 40 afterwards. Frequencies are 5% and 50%, an increase of 45 percentage points. Absolute numbers and frequencies both change here; a different dataset could show frequency rising while total resistant count stays unchanged.
A supplied sample has 18 resistant cells among 60. Find resistant frequency. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A supplied sample has 18 resistant cells among 60. Find resistant frequency.
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The result is 30 %. Known: 18 resistant among 60 cells. Use frequency = resistant / total x 100. Frequency = 18/60 x 100 = 30%. Frequencies and absolute counts can move differently - identify the denominator.
Check the conclusion and its limits
- An incomplete fossil record is not the same as no evidence. A resistant individual surviving does not mean antibiotics gave it an intentional adaptation. Selection and inheritance explain the population change without a goal-directed mechanism.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Evolution requires organisms to choose a useful inherited change. This claim is false: Useful changes arise by random mutation; organisms cannot will them. Selection then favours the useful variants - the population evolves without any individual choosing anything.
Evolutionary evidence: independent lines support an explanation: Each line answers a different question. A fossil gives evidence of past organisms but usually cannot show their complete DNA. A resistance dataset can show population change over generations but is not a complete history of all life. Agreement between inheritance mechanisms, historical records and observed selection strengthens the explanation.
Evolution requires organisms to choose a useful inherited change.
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Useful changes arise by random mutation; organisms cannot will them. Selection then favours the useful variants - the population evolves without any individual choosing anything.
The available fossil evidence of past organisms: write the technical term.
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fossil record means The available fossil evidence of past organisms.