What You Need to Know

Key Concept Diagram

Variation: individuals in a population show differences in their characteristics

Natural selection: organisms with favourable traits are more likely to survive and reproduce ("survival of the fittest")

Inheritance: favourable traits are passed from parents to offspring through genes

Over many generations, the proportion of favourable traits in a population increases

Evidence for evolution: fossil record, comparative anatomy, DNA analysis

Key Vocabulary

Evolution

The gradual change in the inherited characteristics of a population over successive generations

Natural Selection

The process by which organisms with advantageous traits survive and reproduce more successfully

Adaptation

A characteristic that increases an organism's fitness (survival and reproduction) in its environment

Variation

Differences in characteristics among individuals within the same species

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

Which condition is essential for natural selection to occur?

All individuals in a population are identical The environment never changes There is heritable variation among individuals in a population All organisms reproduce at the same rate

Question 2

A population of moths lives on tree bark. Most are pale but some are dark. After industrial pollution darkens the bark, what would natural selection predict?

More pale moths would survive and reproduce All moths would immediately change colour The moths would move to a different environment More dark moths would survive and reproduce

Question 3

What is the main difference between natural selection and evolution?

Natural selection is the mechanism; evolution is the result (change in population over generations) They are exactly the same thing Evolution only applies to animals; natural selection applies to all life Natural selection requires humans to intervene

Evolution and Natural Selection