EVOLUTION BY WAY OF NATURAL SELECTION

1. EVOLUTION BY WAY OF NATURAL SELECTION

2. Species – a type of organism. Reproduction within a species creates the same species. Extinction – the end of a species VOCABULARY

3. What Is Evolution? • The gradual change in living things over long periods of time. • Evolution is a scientific theory, meaning it is a well-tested explanation for the observations made on the Earth.

4. NATURAL SELECTION • The process that causes evolution. • Also called Survival of the Fittest

5. HERE’S HOW IT WORKS • MUTATION OCCURS or • SEXUAL REPRODUCTION CAUSES VARIANCE • NATURAL SELECTION weeds out the weak and allows the strong to survive and reproduce

6. An Example of Natural Selection? The Peppered Moth

7. What is the Peppered Moth? • In England there lives a moth called the Peppered Moth. • It is called the Peppered Moth because it is mainly white with speckles of black on it.

8. The Peppered Moth • In England, the Industrial Revolution began in 1750. • Before 1750 the Peppered Moth looked like this:

9. The Peppered Moth • Before 1750, the Peppered Moth blended in with the trees it liked to live on. • It was CAMOUFLAGED. Tree

10. A Variety of the Peppered Moth • Before 1750 some Peppered Moths had babies that were darker than their parents because of a mutation. All the other Peppered Moths called them freaks because they stood out on the trees. Tree

11. Variety • Both the dark moths and the light moths were called Peppered Moths. • There’s just 2 varieties.

12. A Question for You • Which variety of Peppered Moth was easier to spot by birds who love to eat moths?

13. What Does That Mean? • Because the dark variety is easier to spot, they died often before they could have babies.

14. What Does That Mean? • More of the light variety were able to reproduce. • Less of the dark variety were able to reproduce. • This is called NATURAL SELECTION or Survival of the Fittest.

15. Natural Selection • Since the dark one’s are not as FIT to survive, they will not survive much longer. That’s why Natural Selection is called Survival of the Fittest.

16. The Industrial Revolution • With the coming of the Industrial Revolution, things were about to change for the Peppered Moth. • The Industrial Revolution created factories with chimneys that pumped out dark smoke called soot. • The soot covered everything: buildings, roads, and trees.

17. The Trees Changed colors • Gradually, as the Industrial Revolution kept increasing, more and more soot covered everything. • The bark on trees became darker and darker until they were almost black.

18. The Trees Changed Colors Trees before the Industrial Revolution Trees after the Industrial Revolution

19. A Question for You • Now after the Industrial Revolution, which variety of Peppered Moth was easier to spot by birds who love to eat moths?

20. What Does That Mean? • Because the light variety is easier to spot, more of them died before having babies.

21. What Does That Mean? • Now, more of the dark variety were able to reproduce. • Less of the light variety were able to reproduce. • The light variety was now headed towards EXTINCTION, where no more would be around ever again.

22. What Does All of this Mean? • The more fit organism survives and reproduces (NATURAL SELECTION). • This allows for a change in the species or a entirely new species over long periods of time (EVOLUTION)

23. EVOLUTION • EVOLUTION CAN CHANGE SPECIES • EVOLUTION CAN CREATE NEW SPECIES

24. EVIDENCE OF EVOLUTION FROM COMMON ANCESTOR • COMPARATIVE ANATOMY – similar structures in different organisms • VESTIGIAL ORGANS – no longer have a function; point to earlier times • STRUCTURE OF CELLS & MOLECULES – same in different organisms • MOLECULAR PHYLOGENY – shared genetic code (DNA) • FOSSIL RECORD – evidence in rock