Habitat Havoc Slides
Science Lab Expedition Part 2: Natural Selection
Environmental Pressures
Habitat Havoc:
The Peppered Moth Story
How a sudden change in an environment forced a tiny species to adapt or face extinction.
Classroom Presentation
Let's Explore!
Meet the Species Slide 2 of 6
Two of a Kind
The Peppered Moth lives in England. In the early 1800s, almost all of them were light-colored with dark speckles.
But occasionally, a baby moth was born completely dark black due to a natural variation.
Variation: Naturally occurring differences within the same species.
Type A
The Light Moth
Blended perfectly with pale lichen-covered tree trunks.
Type B
The Dark Moth
Stood out clearly against the bright tree trunks.
If a predator (bird) is flying by, which moth will it spot first?
The Environmental Shift Slide 3 of 6
Industrial Revolution (1850s)
The soot storm that changed everything
Factories Arrive
Coal-burning factories filled the skies of England with thick, black soot.
Trees Turn Black
Lichen on tree trunks died off, and the bark was coated in black soot.
The Shift
Light moths lost their perfect camouflage. Now, they were bright targets!
Environmental Pressure: A change in the habitat that makes it harder for some organisms to survive.
Survival of the Fittest Slide 4 of 6
The Hunted and the Hidden
Before the factories, hungry birds easily caught the rare dark moths because they stood out against bright bark.
After the soot coated the trees, the tables turned! Birds could spot the light moths instantly.
What is "Fittest" now?
"Fittest" does not mean strongest. It means having the best traits to survive and reproduce in the current environment!
Sooty Forest Scenario
Bird Predators
Eat visible moths
Light Moth
Eaten Quickly! 🛑
Dark Moth
Camouflaged! ✅
Over time, dark moths survived and had many babies. What happened to the population?
Evolution in Action Slide 5 of 6
The Numbers Shift
In just 50 years, dark moths went from less than 1% of the population to over 95% of the population!
This is Natural Selection. The environment selected which trait survived.
Moth Population Comparison
Year 1800 (Clean Forests) 99% Light / 1% Dark
Year 1895 (Sooty Forests) 5% Light / 95% Dark
Did individual moths change color? No! The population changed over generations.
👉 Think-Pair-Share: If we cleaned up all the pollution, what would happen to the moths?
Key Learnings Slide 6 of 6
Three Golden Rules of Selection
Write these key concepts down in your Field Notebook!
1
Variations Exist
There must be different physical traits naturally present in a population.
2
Pressure Strikes
The environment changes, creating a challenge where some traits are helpful and others are deadly.
3
Survival of Fittest
The ones with the best matching traits survive, reproduce, and pass those traits to offspring.
Ready to test your skills?
Get out your Peppered Moth Worksheet!
Soot and Survival Worksheet
Ecology Field Journal Case Study: Industrial Melanism
Soot and Survival
Name:
Date:
1. The Clean Lichen Woods (Early 1800s)
Before factories were built in England, the forest trees had light-colored bark covered in pale green lichen (a moss-like plant). The light-colored peppered moths blended in perfectly when they rested on the trees. Hungry birds could not see them, so light moths survived and had many babies.
2. The Great Soot Storm (1850s)
Then came the Industrial Revolution. Thousands of factories burned coal, filling the skies with black smoke. Thick, dark soot coated the forest. The lichen died, and tree trunks turned pitch black. Now, the forest looked completely different.
3. A Sudden Trap
The light moths that used to be safe were now bright white dots against the soot-covered black bark. Birds spotted and ate them instantly. However, a small number of moths were born naturally dark black. These dark moths were now invisible against the soot!
Field Words
Variation
Differences in physical traits that organisms are born with.
Environmental Pressure
A sudden change in a habitat that makes survival difficult.
Adaptation
A trait that helps an organism survive in its environment.
Quick Check
- Light moths: safe on light lichen
- Dark moths: safe on dark soot
Think & Answer (Complete in your own words)
Based on the text above, why did the soot turn from a minor nuisance into a deadly environmental pressure for the light-colored moths?
Because
Page 1 of 2
Ecology Field Journal
Moth Mystery: Cause & Effect
Name:
Step 1: The Cause (Environmental Change)
What physical change happened to the forest habitat during the Industrial Revolution? (Look back at Section 2).
The forest changed because soot
Effect on Light Moths
Why were light moths now in danger?
They could not
Effect on Dark Moths
Why were dark moths now safe?
They were safe because
Step 3: Natural Selection Outcome
Fill in the blanks to summarize what happened over generations:
Because dark moths survived, they had more (offspring).
Over many years, the number of dark moths went , and the number of light moths went .
Critical Thinker Challenge:
Survival Shift Exit Ticket
Quick Assessment Exit Ticket
Survival Shift
How habitats choose who survives.
Name:
Date:
Question 1
What is an environmental pressure?
A
A change in a habitat that makes it harder for certain organisms to survive.
B
The amount of food that an animal eats in a single day.
C
The ability of an animal to change its skin color whenever it wants.
Question 2: Apply Your Knowledge
Scenario: Lava and Lizards
A population of light brown lizards lives on a sandy brown desert. Suddenly, a volcano erupts and coats the desert in pitch black volcanic rock.
Which lizards will have the best camouflage now (the light brown ones or rare dark black ones)? Why?
The lizards will survive best because
Self-Reflection
How confident do you feel about explaining how environmental pressure changes a population?
🌱 Need Some Help I'm still a bit confused.
🌿 Getting There I understand most of it.
🌳 I Got This! I can explain this to others!
Habitat Havoc Exit Ticket Page 1 of 1
