Evolution, Ancestry & Biodiversity — Extension · Life Science: Biology, Grade 10
Explain population change and branching ancestry using independent evidence.
Test Selection and Ancestry Explanations
Investigate
What distinguishes selection evidence from a claim that organisms changed because they needed to?
Use three sessions: define question, boundary, model and route; collect or analyze the supplied repeated records; then graph, explain, revise and submit the notebook. Home-study activities do not certify NYSED laboratory minutes or mandated investigations.
Materials
- Supplied population table
- Calculator
- Graph paper
Before you begin
Use the supplied paper-and-data model. This activity requires no biological samples, cultures, personal health information, or tests on people.
Plan a fair test
Compare pre-existing heritable coat types on two backgrounds under equal model population sizes. The table counts survivors, not lifetime offspring; selection requires evidence of heritability and reproduction as well as survival.
Method
- Predict survival under a visible-predator model without inventing new traits on demand.
- Calculate survival percentages for each coat type on each background.
- Graph the comparisons and identify the interaction with background.
- Predict a generational change if the survival differences also change reproductive success and coat traits are heritable.
- List additional evidence needed to distinguish selection from chance or migration.
- Explain how a population prediction differs from changing one individual’s coat genes.
Open the investigation data (illustrative)
Illustrative data authored for this activity, not an actual experiment or an official mandated investigation. Use them as supplied evidence, not as your own observations.
| Background | Coat type | Starting count | Survivors |
|---|---|---|---|
| Light | Light | 50 | 40 |
| Light | Dark | 50 | 15 |
| Dark | Light | 50 | 10 |
| Dark | Dark | 50 | 35 |
Analyze and explain
- Calculate all survival percentages.
- Which type has higher survival on each background?
- Why do these data alone not measure evolutionary change across generations?
- Separate collected measurements from the supplied illustrative records.
- Explain how labeled mechanisms constrain the pattern rather than only restate the graph.
- Propose a further comparison that could distinguish an alternative explanation.
What a strong explanation includes
- Uses existing variation and environmental comparison
- Calculates rates rather than comparing unadjusted counts
- Connects heritability and reproductive success with population change
- Considers alternatives and requests generational evidence
- State units, boundary, comparable conditions and model assumptions.
- Retain a first explanation and an evidence-supported revision.
Parent / teacher guide: discuss after the investigation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.
Extend the chapter investigation by evaluating its evidence and proposing a better test.
Problem 1
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Problem 2
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Problem 3
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Problem 4
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Problem 5
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Problem 6
Answer and explanation
On the light background survival is 80% for light and 30% for dark; on dark it is 20% for light and 70% for dark. Camouflage under predation is a possible mechanism. If these heritable differences affect reproduction, frequencies may shift across generations. The table alone measures one model survival episode, not allele-frequency change, mutation timing, or ancestry. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.