Evolution Evidence

1. Evolution Evidence The theory of evolution states that all organisms on Earth have descended from a common ancestor

2. Support for Evolution • The Fossil Record (Fig. 15.4 p. 423) • Fossils show that ancient species share similarities with species that live on Earth today

3. Glyptodont Armadillo

4. 2. Comparative Anatomy (Fig. 15.6 p. 425) a) Homologous structures develop from similar tissues in early developmental stages of the organism, but meet different needs in the adult.

5. Homologous Structures

6. Fig. 15.6 on p. 425 • Q: What is similar about each of these? • Similar bone structure, from same tissue •  Q: What is different about each of these? • Perform different functions – grab, walk, fly

7. b) Vestigial structures are features of ancestors that no longer have a function for that species and will become smaller over time until they are lost • Ex: Humans → appendix, tailbone (Table 15.2 p. 425) Snakes →tiny bones where legs used to be

8. Vestigial Structures

9. Other Vestigial Structures • Vestigial Pelvis bone and femur in whales

10. Other Vestigial Structures

11. c) Analogous structures look similar in appearance and function, but are developed from anatomically different parts • They are used for the same purpose and similar in construction, but not inherited from a common ancestor. • Ex: eagle wing vs. beetle wing (Fig. 15.7) bird wing vs. bat wing

12. Analogous Structures

13. 3. Comparative Embryology (Fig. 15.8 p. 426) • Embryology is the study of embryos • Embryo = early, pre-birth stage of an organism’s development • Vertebrate embryos have similar structures during certain stages of development, but become totally different structures in the adult form.

14. Comparative Embryology

15. Comparative Embryology Human embryo Chick embryo (LM) Pharyngeal pouches Post-anal tail

16. Q: What do similarities in early development indicate? • The organisms have similar genes controlling early development. Q: What do these similar genes indicate? • These organisms have a common ancestor. Q: Why do the embryos become different as they develop? • Different genes start to contribute or become “expressed” in the organism.

17. 4. Comparative Biochemistry (Fig. 15.9 p. 427) • Evolutionary theory predicts molecules in species with a recent common ancestor should share certain amino acid sequences. • The more closely related the species are, the more amino acid sequences they have in common.

19. 5. Geographic distribution (Fig. 15.10 p. 427) • Evolution is linked to climate and plate tectonics which explains many ancestral relationships and geographic distributions seen in fossils and living organisms. • For example: South American animals are more similar to other South American animals than to animals in Europe.

20. Mara – South America Rabbit – Europe

21. Adaptation • An adaptation is a trait influenced by natural selection that increases an organism’s reproductive success.

22. Fitness: The ability of an organisms to survive and reproduce • how much a certain trait appears in the next generation; measured by the amount of offspring

23. Camouflage: adaptation that allows a species to blend in with their environment. • Why? • Hide from predators/prey, more survive to reproduce • Ex: Arctic fox (Fig. 15.11 p. 428)

24. Leafy sea dragon

25. Mimicry: one species changes to look like another species • Ex: Harmless snake “mimics” a poisonous snake so predators leave it alone (Fig. 15.12 p. 429)

26. California Kingsnake Western Coral Snake (poisonous)

27. Antibiotic resistance: • Some species of bacteria that originally were killed by antibiotics (like penicillin) have evolved to be drug resistant • For nearly every antibiotic, there is at least one species of resistant bacteria

28. Example: Tuberculosis (TB)