1. F. DARWIN’S EVIDENCE FOR EVOLUTION

2. 1. Fossils - fit a pattern

3. 2. Homologous structures
similar structures doing very different functions
a. bones in adults

4. Tiktaalik was discovered in 2006

5. b. structures in embryos
fish salamander turtle chicken pig mouse dog human

6. fish salamander turtle chicken pig mouse dog human

7. fish salamander turtle chicken pig mouse dog human

8. 3. vestigial features
structures with no function in one organism but have a function in similar organisms
eg human appendix,
The appendix of the gorilla is massive, accounting for its ‘fat’ stomach.
This appendix houses bacteria that breakdown cellulose

9. whale pelvis
A whale pelvis has the same bones as land animals, but is not attached to the spine and so is useless.

10. 4. artificial selection
a. dogs
All of these dogs have a recent common ancestor.

11. b. pigeons
Darwin kept pigeons and was familiar with their breeding and how almost any trait could be selected for by the breeder..

12. the key is that artificial selection happens much faster
as humans discard the unsuitable breeders

13. 5. Mechanisms of Darwinian Evolution by Natural Selection
ASSUMPTIONS
1. offspring vary
Note the differences among these kittens.

14. 2. some of this variation is heritable
Setters produce setter pups, not retriever pups.

15. 3. more offspring are born than can survive
If all of these baby spiders survived, the world would be overrun!

16. 4. populations generally do not increase in size

17. INFERENCES
1. individuals of the same species will compete
2. the survivors will pass on their ‘favourable’ traits to the next generation
3. over time, there will be more traits from the survivors in the population

18. 6. Macroevolution vs Microevolution
Macroevolution – change to form new species
many species arising from one common ancestor
eg Darwin’s finches
this takes a very long time
[10,000’s  millions of years]

19. Microevolution - change within a species
this takes only a short time
[10’s 1000’s of years]
eg. bacteria antibiotic resistance
all were sprayed with herbicide but one remains green
and weeds herbicide resistance

20. In this one species, there are two forms of moths
eg. peppered moths
light-coloured pre-Industrial trees
Prior to industrialization, the light form was most common

21. light-coloured pre-Industrial trees
dark-coloured post-Industrial trees
prior to industrialization, the light form was most common
after industrialization, the dark form became the most common
Studies showed that predators selected the easier to find moths

22. Darwin’s explanation for the longer necks in giraffes?
He knew that some baby giraffe’s are born with slightly longer necks.
There is limited food and so these longer-necked giraffes might get more food and do better.
Over time, more of the population would consist of loner necked giraffes.
But Darwin was wrong!!

23. Neck length is giraffes has nothing to do with food
Giraffes spend most of their time eating low, not high
And bending down to get a drink is very awkward
So why do giraffes need long necks?
For fighting!!