1. Do Now
Do you think these two organisms evolved from a common ancestor?
What evidence would you need to convince yourself?

2. Do Now: Gather the following...
Evidence for Evolution handout in front (everyone)
1 laptop per table
Open to our Schoology page
PowerPoint and Notes Folder
Evidence for Evolution WebQuest Links Folder

3. Evidence for Evolution

4. Group Work: Fossil Record

5. Fossil Record Layers of rock contain fossils
Newer layers of rock cover older ones
Creates a timeline
Fossils can show a record of organisms that lived on Earth over a long period of time

6. What can you infer from this illustration???
Is there a transitional fossil?
Punctuated equilibrium
Is this gradualism or punctuated equilibrium?

7. Fossil Record
Many fossils link early extinct species with species living today
Example: Tiktaalik- “missing” link between land and sea animals.

8. A transitional species: Tiktaalik

9. Tiktaalik (2006) Like a fish complete with scales and gills
Flattened crocodile head with unusual fins
sturdy interior bones that would have allowed Tiktaalik to prop itself up in shallow water and use its limbs for support as most four-legged animals do.

10. Transitional Species: Aetiocetus

11. Horse Lineage

12. Transitional Species: Thrinaxodon
Ancient reptile Thrinaxodon ancient mammal

13. Group Work: Embryological Evidence

14. Embryological similarities
Embryos of related species show similar patterns of development in early stages
Ex. Pharyngeal slits
= evidence for common ancestor
Pharyngeal slits
Pharyngeal slits
Hox genes- homeobox genes- group of related genes that control the body plan of an embryo along the head-tail axis
Genes give information for segment identity, but do not form actual segment themselves
Discovered Hox genes because of mutations:
UBX gene (ultabithorax) duplicates thorax and gives you two
AntP (antennapedia gene)- grow legs out of the head of fruit fly
Pharyngeal slits-
In fish- turn into gills
In mammals- develop into eustacian tube, middle ear, tonsils, parathyroid and thymus
= same structures in embryo turn into different functions in different species

15. Hox Genes

16. Group Work: Homology

17. Comparative anatomy
Refers to structural similarities found between related organisms Homologous structures – Limbs that perform different functions but are built from the same bones
Human
Cat
Whale
Bat

19. Convergent Evolution: Analogous Structures
Similar function but different structure
Structures that resemble each other due to similar selective pressures and not to recent common ancestry

20. Convergent Evolution
Species that are only distantly related (do not share a recent common ancestor) develop similar adaptations and resemble each other
They live in similar environment and are exposed to similar selective pressures

21. Group Work: Vestigial Structures

22. Vestigial Structure: cavefish
Remains of structures that were functional in ancestors
Eyes on a blind cave fish

23. Vestigial Structure: EMU

24. Vestigial Structure: Whale
Remains of structures that were important to the organisms’ ancestors but are not to the existing organisms

25. What about vestigial structures in humans?
Long tail used for balance
Ears more alert to predators
Goosebumps make hair stand up, keep warm, scare predators
Little toe was used for balance
Wisdom teeth: used for grinding hard foods/leaves

26. Group Work: Comparative Biochemistry

27. Comparative Biochemistry
Similarities in DNA and proteins
Amino acid sequences can be compared among various species for minor changes
The more similar the code, the closer related

28. Biochemical/Molecular Data
Types of Organisms
human
monkey
pig
duck
turtle
fish
moth
yeast (Candida) 10 20
Number of Amino Acid Differences Compared to Human Cytochrome c 30
Branch points tell the number of amino acids that differ between human cytochrome c and the organisms depicted 40 50

30. Percent Agreement between Beta Globin of Various Species
Human
Chimp
Gorilla
Red fox
Dog
Polar bear
Horse
Rat
Chicken
100.
99.3
91.1
89.7
83.6
81.5
69.2
91.8
90.4
82.9
80.8
68.5
98.6
95.2
80.1
72.6
94.5
79.5
71.2
71.9
76.0
67.8
65.8

31. Biogeography Geographic distribution of species
How could this be evidence?
Darwin notes that tortoise species in tropical Galapagos more closely resembled tortoises on the mainland than those on distant tropical islands
Similar species = descendents of immigrants
There was a closer match between geographically nearby species, even when the environments for the two differed THAN there was between that species and other species living in the same type of environment but geographically distant

32. SUMMARY SHEET What do you think?
Of these four (in your packet), which do you think is the strongest evidence for evolution?