Selective Breeding Uses the Same Mechanism, and Has a Cost

Lab Brief #4

🎯 Your mission

Master the concept. Use it tomorrow.

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

Artificial selection works through exactly the mechanism natural selection uses; only the agent choosing which variants reproduce is different, and because the pressure is intense it works fast — maize was bred from teosinte in a few thousand years. The cost is narrowed variation. Breeds pushed hard toward one trait carry a burden of inherited disease, and a population with little genetic variation has little to draw on when conditions change, which is why crop gene banks exist.

Key words

artificial selection
Deliberate choice by humans of which individuals reproduce, in order to make a desired trait more common.
genetic variation
The range of different alleles present in a population, which is reduced by intensive selective breeding.

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 "artificial selection" and "genetic variation" mean in your own words before you start.

Step 2 of 4 · Do

Compare photographs of teosinte with modern maize and of a wolf skull with four dog breeds, measuring one proportion in each. Then research one inherited disorder linked to a heavily selected breed and explain how narrowing variation produced it.

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

Artificial and natural selection differ mainly in:

How sure are you?😐 maybe

Question 2 of 3

A main cost of intensive selective breeding is:

How sure are you?😐 maybe

Question 3 of 3

Gene banks are maintained mainly to preserve:

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: Speciation Requires a Barrier to Gene Flow All lessons

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Selective Breeding Uses the Same Mechanism, and Has a Cost

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Selective Breeding Uses the Same Mechanism, and Has a Cost

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