1. Homologous Structures and Embryos
Write in complete sentences!
Don’t talk during the Catalyst!
HW on your desk!
Catalyst
Whales evolved from mammals. Do they have more DNA in common with cows or sharks?
Humans share 30% of their DNA with daffodils, and 65% of their DNA with frogs. Which animal are they more closely related to?
Land animals evolved from animals that lived in the ocean. Draw a transitional fossil between the two.

2. By the end of today, all SWBAT…
Objectives
By the end of today, all SWBAT…
Explain how homologous structures support the theory of evolution
Compare the development of different animal embryos

3. Agenda Catalyst/HW Review Homologous Structures Guided Practice
In Embryos
Guided Practice
Independent Practice/Homework
Closing
Exit Questions

4. Catalyst Review
Whales evolved from mammals. Do they have more DNA in common with cows or sharks?
Cows!
The more DNA an organism shares with another, the more closely related they are.
Humans share 30% of their DNA with daffodils, and 65% of their DNA with frogs. Which animal are they more closely related to?
Humans are more related to frogs than daffodils.

5. Catalyst Review
Land animals evolved from animals that lived in the ocean. Draw a transitional fossil between the two.
A transitional fossil is the fossil of an organism that has traits in between its ancient ancestors and species that came after it.

6. Homework Review
What two classes of mammals does the transition from Pakicetus to Basilosaursus represent?
Why do biologists classify at Pakicetus as an early aquatic mammal?
What structure does Basilosaurus have that hints at its evolutionary past?
If you’re worried about time, skip the homework review and do it on Thursday (review day for unit test)

7. Homework Review
What was the largest difference between Australopithecus afarensis and Dryopithecus?
The largest difference between…
From the picture, what do you think “quadrupedal” and “bipedal” mean?
I think quadrupedal means…
Which fossil would you most likely find deepest in the rock layer?
In the deepest rock layer, you would find the fossil for…
If you’re worried about time, skip the homework review and do it on Thursday (review day for unit test) 7

8. Human Evolution Homo habilis H. ergaster H. erectus H. heidelbergensis
H. sapiens and H. neanderthalensis
Homo habilis = oldest species in Homo genus, made tools from stone and bone, short, long arms, 50% sized brain
Homo ergaster = longer, less ape-like body; 74% sized brain
Homo erectus = first to walk upright, larger brains than habilis
Homo heidelbergensis = larger brains (more advanced tools), sensitive ears (differentiate between different sounds), right-handed. Sima de los Huesos pit is the first evidence of funerary.
Homo sapiens and Homo neanderthalensis

9. Side-by-Side

10. Comparative Anatomy
Scientists can compare the anatomy of different organisms to figure out how closely they are related.
Anatomy = body structure
Remember, the theory of evolution tells us that all life branched off from one original species (red circle) and the more closely two organisms are related, the more recently they shared a common ancestor

11. EVOLVE
Happens

12. Homologous Structures
Homologous structure: Part of different species that have the SAME structure and position
Key Point #1: Homologous structures show that two species evolved from a common ancestor
Common Ancestor: One organism that different species evolved from
Two species possess a homologous structure BECAUSE they both inherited it from a common ancestor
Remember, homo = same
Introduce definition first (explicitly state that this is satisfying our first objective), KP explains why it’s important (b/c it provides a certain sort of evidence for evolution… hey, our second objective!). Then, CFU: can you explain to me how homologous structures support evolution? (All they have to do is spit KP back out at you… but make sure they can do it.)

13. Humans, cats, whales, and bats all inherited their forearm from the same common ancestor
Orange = ulna, white = radius, wrist bones, carpals

15. Pigs and humans both have pancreases that produce insulin
Pig and human pancreases are _______ structures.
What does this tell us about human/pig evolution?

16. Embryos Key Point #2: All animal embryos have gill slits and tails
Embryo = organism in the early stages of its development
What type of structures are these?
Think-pair-share: What does this tell us about animal evolution!?
In fish, embryonic gill slits develop into gills. In mammals, embryonic gill slits develop into the throat and ear bones.
Tails are found in embryos—both animals that have tails as adults (dogs, cats, etc.) and animals that lack tails as adults (frogs and HUMANS!!!)

17. Human embryo Chicken embryo
Lookin’ good!
Human embryo Chicken embryo

18. The fact that all animal embryos have gill slits shows that ALL animals evolved from the SAME common ancestor

19. The fact that all animal embryos have tails shows that ALL animals evolved from the SAME common ancestor

20. Which one is the cow embryo?
cat cow horse human

21. Notes Reflection ADD IT!!!
How do homologous structures provide evidence for evolution?
Homologous structures show that two organisms evolved from a common ancestor
If you can’t find the answer…
ADD IT!!!

22. Notes Reflection ADD IT!!!
What parts of animal embryos are homologous?
Gill slit
Tail
That organisms
If you can’t find the answer…
ADD IT!!!

23. Notes Reflection ADD IT!!!
What do homologous structures in animal embryos tell us about their evolution?
All animals evolved from the same common ancestor
That organisms
If you can’t find the answer…
ADD IT!!!

24. SWITCH!!! Test Prep (6 minutes)
What is the definition of a homologous structure? Give one example.
Explain how homologous structures, in general, tell us about how two species evolved.
Dog feet and lizard claws are examples of homologous structures. What do these structures say about how dogs and lizards evolved?
SWITCH!!!

25. SWITCH!!! Test Prep (6 minutes) What is an embryo?
What parts of animal embryos are homologous?
What does this imply about animal evolution?
At the beginning, all animal embryos look very similar. What happens as they each develop?
SWITCH!!!

26. SWITCH!!! Test Prep (10 minutes)
Juanita says that frogs cannot be related to bears because adult frogs look so different from adult bears. Explain to her how we can use the appearance of frog and bear embryos to prove that they are related.
Daniel notices that all organisms use the same four bases in their DNA: A, T, G, and C. What does this tell us about how they evolved?
SWITCH!!!

27. Independent Practice (IP)
Get an early start on the homework.
Tomorrow’s HW is on the back. DO NOT LOSE THIS SHEET.

28. Key Point Wrap-Up
Key Point #1: Homologous structures show that two species evolved from a common ancestor
Key Point #2: All animal embryos have gill slits and tails
These are homologous structures
All animals evolved from a common ancestor!!!
Get a volunteer to read KP1, second volunteer to explain how KP1 fulfills the first objective, third volunteer to explain how KP2 fulfills the second objective
Repeat with KP2, KP3

29. Exit Question: Choose one option Write in complete sentences!
What is one thing that human embryos and dolphins embryos both have in common?
What kind of structure is this?
How do these structures provide evidence for evolution?
Dogs and alligators both have long snouts that allow their jaws to open wide.
What kind of structure is this?
How do these structures provide evidence for evolution?
Student Choice – there’s a WOW factor!