1. EVOLUTIONARY THEORY
Evolution= Gradual change over time

2. Adaptation
Adaptations are inherited traits that increase a group’s chance of
survival & reproduction
This type of finch has a thick beak  adaptation for cracking open seeds

3. Variation Within a species, there is variation
Variation = differences between members of a population
Species = group that can breed & produce healthy offspring

4. The Scientists
Jean Baptist Lamarck
vs.
Charles Darwin

5. are passed to offspring.
Jean Baptiste Lamarck Evolution occurs as structures develop through use, or disappear because of disuse, and these “acquired characteristics”
are passed to offspring.
EXAMPLE:
Over a giraffes lifetime it can stretch it’s neck and it’s offspring will be born with long necks….
Valid?

6. Darwin and The Monkey!
THIS IS NOT WHAT HIS THEORY SAYS

7. Who was Charles Darwin Studied medicine Received a BA in Theology
Hated the sight of blood
Received a BA in Theology
Had 10 children
Darwin was a Naturalist
on the HMS Beagle

8. Theory of Evolution
In The Galapagos Islands, Darwin collected species of finches (13)
Each had a specialized diet and beak structure
These finches all closely resembled a South American finch ancestral species
On the trip Darwin saw things he could only attribute to a process called:
“Natural Selection”

9. Darwin’s Finches

10. Theory of Evolution
Hypothesized that the differences were do to gradual change
Darwin referred to such change as “descent with modification” – evolution;
Wrote Origin of Species
He still wondered
“How does evolution occur?”

11. After his voyage, Darwin made the following inferences:
There is variation within populations
Some variations are favorable
Not all young produced in each generation can survive
Individuals that survive and reproduce are those with favorable variations
Favorable traits will increase in future generations.

12. Darwin called this process by which populations change in response to their environment:
Natural Selection

13. So....What is Evolution?

14. Evolution happens because of natural selection
Selection acts on individuals, populations evolve

15. Change creates advantages for some species & disadvantages for others
Fossils reveal changes in species over millions of years

16. Evidence for Evolution
Fossils
show change over time
scientists can date fossils & use them to support the theory of evolution
common ancestors reveal whether species are related
Anatomy of living species also
shows relatedness

17. How Anatomy supports Evolution
Homologous Structures
Traits similar in different species because they share a common ancestor
Ex: human arm, dog front limb, horse leg, whale fin
These “ look the same.” They have the same bones but different function. An

18. How Anatomy supports Evolution
3. Analogous structures
Distantly related species have structures that have the same function but are different in structure
Ex: wing of butterfly & bird
These “ work the same.” They have different bones but the same function.

19. How Anatomy supports Evolution
4. Vestigial structures
Structures reduced in size & often unused
Remains of functional structures inherited from an ancestor
Ex: leg & hip bones in pythons & whales

20. How DNA Supports evolution
5. Molecular Evidence
Also called biochemical evidence
Compares biomolecules such as DNA or amino acid sequences between organisms
Related organisms have more of the same molecules in common

21. So….. Where Do New Species Come From?

22. How do new species form? Geographic Isolation
When members of a population are separated
Ex: polar, grizzly, & black bears

23. 2. Reproductive Isolation
When members of a population can’t breed even though they live nearby
Ex: different mating seasons or different mating calls

24. Different Types of Evolution
Divergent evolution
Convergent evolution
Coevolution
Adaptive radiation

25. Divergent Evolution -Isolated populations evolve independently
Ex: polar & grizzly bears changed independently due to different habitats

26. Convergent Evolution
-Unrelated species become more alike because they live in similar environments
Ex: shark & dolphin

27. Coevolution -Species that interact closely adapt to one another
Ex: Flowers & Pollinators
(Birds, Bees and Butterflies too)

28. Adaptive Radiation
Evolution of many diverse species from one common ancestor
Ex: famous Galapagos finches discovered by Darwin

29. Questions?