1. DO NOW
What is fitness?
If an organism does not have high fitness what will happen to it? What will happen to its species?
In natural selection, what decides the best traits to “keep”
What are changes in genetic info called?
What is a fossil?

2. Evidence for Evolution
Objectives:
Understand homologous structures
Be able to give an example of a vestigial structure
Know that molecules can also be vestigial

3. Vocabulary Homologous structures Analogous structures
Vestigial structure
Homologous Protein
Homologous Genes

4. Evidence for Evolution
By Darwin’s time, scientists had noted that all vertebrate limbs had the same basic bone structure.

5. Common Descent
Common descent – all organisms on this planet come from a single common ancestor
This was from Monday’s vocabulary

6. Comparing Anatomy and Embryology
The front limbs of amphibians, reptiles, birds, and mammals contain the same basic bones.

7. Homologous
Darwin proposed that animals with similar structures evolved from a common ancestor with a basic version of that structure.
homologous structures - Structures that are shared by related species and that have been inherited from a common ancestor

8. Homologous Structures

9. Analogous Structures
Analogous structures – structures that share a common function, but not structure

10. Vestigial Structures
Vestigial Structures – structures that have lost much or all of their original function
Vestigial structures/ vestigial genes are some of the strongest evidence for evolution

11. Brainstorm!

12. Vestigial Structures
Dolphins have hip bones that do nothing, heck they aren’t even attached anymore!

13. Vestigial Structures

14. Vestigial Structures

15. Refresher Proteins are made of amino acids
The instructions for making proteins comes from DNA
The flow of information in a cell (any cell) is DNA -> RNA -> Protein
Question:
If the DNA is changed what happens to the protein?

16. Vestigial Genes
In our Genome (our DNA) we have the genes that code for things our ancestors had, but we no longer need.
These genes have been sitting in our DNA for millions of years
Every once in a while, these genes are expressed.
Because they have been dormant for so long they often do not work very well.

17. Atavisms
Atavisms also are called "throwbacks" and can be found in modern horses and their relatives despite millions of years of evolutionary separation from their fossil horse ancestors.

18. Atavisms
Atavisms are caused because we still have the DNA from our ancient ancestors.

19. Chicken With Teeth

20. Homologous Molecules
Homologous proteins – proteins that share extensive structural and chemical properties.
That means that they do the same job and look similar.

21. Homologous Genes
Homologous genes – are genes that perform the same task
These are NO DIFFERENT that homologous alleles

22. Homologous Genes

23. Embryology

24. DNA these letters also spell DAN
Everything we are is just an expression of DNA
Your eye for example, is at its core nothing more than thousands of T’s G’s C’s and A’s.
If one of those T’s G’s C’s or A’s is changed then it is possible that the structure of the eye will change as well.
Every time your cells go through mitosis mistakes are made in the DNA
Over time these mistake add up
We can actually tell how closely related to species are by looking only at these mistakes

25. Exit Ticket
What is the difference between a homologous structure and an analogous structure?
Give an example of a vestigial structure.