Natural Selection Needs Three Conditions at Once

Lab Brief #1

🎯 Your mission

Master the concept. Use it tomorrow.

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

Natural selection requires variation between individuals, heritability of that variation, and a difference it makes to survival or reproduction. Remove any one and nothing evolves — which is why a bodybuilder's muscle, acquired within a lifetime and not heritable, changes no population at all. Selection also never creates the variation it acts on; mutation does that, and selection only changes how common existing variants become.

Key words

heritability
The degree to which variation in a characteristic is passed from parents to offspring through their genes.
natural selection
The process by which heritable variation that improves survival or reproduction becomes more common over generations.

Make a hypothesis first

Before you start: write down what you think will happen, and why.

Say your guess out loud — then find out if you were right.

Step 1 of 4 · Read

Think about what you just learned: say what "heritability" and "natural selection" mean in your own words before you start.

Step 2 of 4 · Do

Model selection with 100 paper discs, half camouflaged and half bright, scattered on patterned cloth. Take a timed 20-second 'predation' round, remove what you found, let the survivors double, and repeat for four generations, recording the proportions each time.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 3

Which of these is NOT required for natural selection?

How sure are you?😐 maybe

Question 2 of 3

A bodybuilder's acquired muscle does not evolve a population because it is:

How sure are you?😐 maybe

Question 3 of 3

The source of new variation in a population is:

How sure are you?😐 maybe

Mind = blown

🔬 The more you look, the more nature shows you.

Nice work!

You got 0 of 3 right.

Next: Antibiotic Resistance Is Selection You Can Watch All lessons

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🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

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👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

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Natural Selection Needs Three Conditions at Once

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