Worksheet on the peppered moth and natural selection in evolution.

It looks like you've uploaded a page from a biology textbook discussing "The Peppered Moth" and its role in illustrating the mechanisms of evolution, specifically natural selection. The text describes how the peppered moth (*Biston betularia*) underwent a shift in coloration due to industrial pollution, which provided strong evidence for natural selection.

Let me break down the content and help you solve the tasks presented on this page:

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🔍 Summary of the Text:

- The peppered moth has two forms:
- Light-colored (typical) form: Camouflaged against lichen-covered trees.
- Dark-colored (melanic) form: Rare before the Industrial Revolution.

- During the Industrial Revolution:
- Trees became covered in soot.
- Lichens died off, exposing dark bark.
- The dark moths became better camouflaged.
- Predators (like birds) were more likely to eat light moths now exposed on dark surfaces.

- As a result:
- Dark moths had higher survival rates.
- Their frequency increased in populations.
- This is a classic example of natural selection in action.

- When air pollution decreased later, lichens returned, and the light moths regained their advantage.

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✔ Tasks and Solutions:

#### 1. "In what way did the peppered moth change over time? What did the black moth come from?"

Answer:
- Over time, the frequency of dark-colored (melanic) moths increased in polluted areas during the Industrial Revolution.
- The black moth came from a genetic mutation that produced a darker pigment in the wings.
- This mutation was already present in the population but was rare because it was disadvantageous when trees were light-colored.
- With environmental changes (sooty trees), the mutation became advantageous, and natural selection favored the dark form.

> 🌟 Key Concept: Natural selection acts on existing variation—the dark form didn’t evolve *from* the light one; it existed as a variant and became more common due to environmental pressure.

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#### 2. "Explain how the peppered moth example fits with those reasons that Darwin and others considered evidence for evolution."

Answer:
Darwin and other scientists looked for evidence showing:
- Variation exists within populations.
- Some traits improve survival and reproduction (adaptations).
- Offspring inherit traits from parents.
- Populations change over generations.

The peppered moth example supports all these points:

1. Variation: There are light and dark morphs.
2. Differential Survival: In polluted areas, dark moths survived better.
3. Heritability: The color trait is genetically inherited.
4. Change over Time: The proportion of dark moths increased in response to environment.

This real-world observation provided strong empirical evidence for natural selection, confirming Darwin’s theory.

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#### 3. "Explain how the peppered moth example fits into the model of natural selection."

Answer:
The peppered moth perfectly illustrates the four steps of natural selection:

1. Variation: Individuals differ in color (light vs. dark).
2. Overproduction & Competition: Moths produce many offspring; not all survive.
3. Struggle for Existence: Birds prey on moths; camouflage affects survival.
4. Differential Survival and Reproduction:
- On darkened trees, dark moths survive better → reproduce more.
- Light moths are eaten → fewer offspring.
5. Inheritance: Offspring inherit color genes.
6. Change in Population: Over generations, the frequency of dark alleles increases.

✔ So, the moth example shows how environmental change leads to shifts in allele frequencies—a core mechanism of evolution by natural selection.

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🧠 Final Takeaway:

The peppered moth is one of the most famous examples of evolution in real time. It demonstrates:
- How natural selection can cause rapid evolutionary change.
- That environmental pressures shape the traits seen in populations.
- That genetic variation is essential for adaptation.

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