Today ’ s Agenda

1. Today’s Agenda • Costa Rican Example • Dry Lab • Guided Notes Lecture • MacroEvolution Final Assessment • MicroEvolution Test Return

2. The Glass Frog H. ruedai

3. MacroEvolution COMPARATVE ANATOMY Importance & Evidences

4. Why do we care? Curiosity Practicality An intrinsic reason: evolution tell who’s related to whom and how we all came to be. An extrinsic reason: if we want to preserve an environment compatible with human life, we’d better know what’s out there.

5. Learning Target: I can explain how… multiple lines of scientific evidence support biological evolution

6. each node indicates a common ancestor An example PHYLOGENY for vertebrates • The greater the number of characteristics shared by a pair of organisms, the closer their degree of relationship. • The closer the degree of relationship, the closer the most recent common ancestor.

7. It’s important, but often difficult, to distinguish from Homology Analogy

8. Mini Vocab Lesson… ANALO- means: LIKE or SIMILAR Think – Analogous colors are near each other on the color wheel • HOMO- means: SAME • Think – Homo sapiens are the same as us

9. What is an example of an Homology? ThinkPairShare

10. Homology These are similar because they are derived by modification of a shared ancestral structure. Homologous structure examples: the human arm, lizard foot, whale fin, and bird wing. Homology is the key to establishing phylogenies.

11. Homologies are everywhere! The leaves of an oak (left) and the leaves of a gingko (right) are homologous — they were both inherited from a common ancestor with leaves. The buckteeth of the beaver(left) and the tusks of the elephant(right) are homologous — they were both inherited from a common ancestor with incisor teeth.

12. Analogy, from ConvergentEvolution Similarities that are NOTdue to common ancestry Just because two organisms have a common trait, does not necessarily mean they share a common ancestor.

13. Convergent Evolution Different species adapt in similar ways when challenged by similar opportunities. • Basically, natural selection is consistent!

14. Homology or Analogy? You have probably noticed that dolphins and sharks both have a streamlined body shape with a triangular fin on the back and two side fins. However, the two animals also have many differences. http://www.pbs.org/wgbh/evolution/library/03/4/quicktime/l_034_05.html Do you think that sharks' and dolphins' similarities (body shape, fin, and flippers) are homologies or analogies?

15. Homology or Analogy? You have probably noticed that dolphins and sharks both have a streamlined body shape with a triangular fin on the back and two side fins. However, the two animals also have many differences. Do you think that sharks' and dolphins' similarities (body shape, fin, and flippers) are homologies or analogies?

16. ThinkPairShare Analogy or Homology?

17. They’re analogies  Dolphins and sharks are on distant branches of the tree of life. Sharks are closely related to rays, and dolphins are closely related to cows and other mammals. Streamlined bodies and fins are traits that dolphins and sharks evolved separately, both as adaptations for swimming.

18. Studying homologies & analogies • Same basic structure • Same relationship features EXAMPLE: The same bones (though differently shaped) support the limbs of terapods (four legged animals). EXAMPLE: The limb bones are connected to the skeleton in similar ways in different tetrapods. The joint between the femur and the pelvis has a ball-and-socket structure, as shown in this crocodile.

19. Homology or Analogy? Sugar gliders and flying squirrels look amazingly similar. They are both furry animals of about the same size, with big eyes and a white belly. And they both glide from treetops using a thin piece of skin that is stretched between their legs. This piece of skin helps keep them stable while gliding. Are the "wings" (flaps of skin stretched between the legs) of sugar gliders and flying squirrels homologous or analogous structures? Sugar Glider Flying Squirrel

20. ThinkPairShare Analogy or Homology?

21. They’re analogies  Since sugar gliders and flying squirrels are very distantly related, it seems very unlikely that their common ancestor had flaps of skin stretched between its legs and that both modern animals inherited the trait from this animal. Instead, each lineage probably evolved the trait independently as adaptations for gliding and tree-living.

22. Vestigial Structures A feature that an organism inherited from its ancestor but that is now less elaborate and functional than in the ancestor. Fish species that live in completely dark caves have vestigial, non-functional eyes. When their sighted ancestors ended up living in caves, there was no longer any natural selection that maintained the function of the fishes' eyes. Today, these fish still have eyes — but they are not functional and are not an adaptation; they are just the by-products of the fishes' evolutionary history. Usually, vestigial structures are formed when a lineage experiences a different set of selective pressures than its ancestors, and selection to maintain the elaboration and function of the feature ends or is greatly reduced.

23. Examples of Vestigial Structures in Humans • Appendix? • Tailbone/Coccyx? • Wisdom Teeth? • Male Nipples? • Goose Bumps? • Junk DNA?

24. Further Evidence • Embryology • Molecular Biology Similar Development – EXAMPLE: The limbs of all tetrapods develop from limb buds in similar ways. Using DNA or Amino Acid Sequences EXAMPLE: Polar Bears vs. Grizzlies

25. Connecting Our Understanding • Evolution Research Projects!