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Lesson · Grade 7 · Science

What evolution means: populations change over time

  • Grade 7
  • Science
  • 1 min 7 s
  • British Columbia
  • BC7-SC-01

A population of green and brown beetles lives on brown ground, where a bird spots and eats the green ones more easily, so more brown beetles survive and pass their colour on to their young. Over three generations along a time arrow the mix goes from 7 green and 3 brown to 1 green and 9 brown, showing that no single beetle changes but the population does, and that this change over many generations is called evolution.

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In one sentence

The question this lesson answers

What does the word evolution really mean?

Here is a population: a group of beetles of the same kind, living in one place.

Transcript

What the lesson says

What does the word evolution really mean?

Here is a population: a group of beetles of the same kind, living in one place.

The beetles are not all the same. Some are green and some are brown.

On brown ground, birds spot the green beetles more easily, and eat them.

So more of the brown beetles survive.

The survivors have young, and the young get their colour from their parents.

So the next generation has more brown beetles than before.

The same thing happens again, in every generation.

After many generations, most of the beetles are brown.

The population has changed over time.

But no single beetle changed its colour during its life.

This change in a population, over many generations, is called evolution.

Evolution means a population changes over many generations.

Curriculum

Where this fits

British Columbia, Grade 7

Science, Biology: organisms have evolved over timeBC7-SC-01

Next: Individuals do not evolve, populations do

The outcomes and strands follow the British Columbia curriculum.

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