Evolutionary Classification

1. Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth. Evolutionary Classification

2. Geologic History • Geologic time- time that began when earth was formed until present day

4. Evolution of the Earth with Time: Continental Drift 50 Million Years Ago 200 Million Years Ago 150 Million Years Ago 100Million Years Ago Present

5. Important Terms • Evolution- gradual change in a species over time- sci. theory • Theory-well-tested explanation that explains a wide range of observations. • Adaptation- any trait that helps an organism survive and reproduce

6. Natural Selection- • the process by which individuals that are better adapted to their environment are more likely to survive and reproduce. • Charles Darwin

7. Natural Selection cont. • Over a long time, natural selection can modify a population enough to produce a new species • Helpful variations accumulate in a species while unfavorable ones disappear.

8. Speciation • When a group of individuals remain separated from the rest of the species long enough to evolve different traits

9. How Speciation Occurs • Geographic isolation- • Pangaea /Continental Drift • Landform isolation- river, mountain, water. (ex. Squirrels of N. Grand Canyon) • Competition • Gene flow • Environmental change- local adaptation to local environment

10. Speciation of Squirrels- Grand Canyon • The Kaibab squirrel (Sciurusabertikaibabensis, left) became isolated in the Grand Canyon ~ 10,000 years ago. Features have gradually evolved that separate it from close relative, the Abert squirrel (S. abertiaberti)

11. A Problem with Traditional Classification Example: The Crab, The barnacle, & The limpet • The barnacle and the limpet have similarly shaped shells & look alike • The crab has a very different body form • Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.

12. Related This incorrect because crabs and barnacles are actually related

13. Crustaceans Gastropods Molted Exoskeleton Even though they do not look a like, crabs & barnacles are actually related Segmentation Free swimming Larva

14. A Problem with Traditional Classification • Traditional classification systems relied on body structure comparisons only • Due to convergent evolution, organisms that are quite different from each other evolve similar body structures. Convergent Evolution: Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

15. Modern Evolutionary Classification Evolutionary Classification: Is the strategy of grouping organisms together based on their evolutionary history, instead of physical features. Uses DNA and RNA, embryological development, comparative anatomy to classify species.

16. Modern Three-Domain System • As scientists further analyzed cell structure and DNA , a broader category was added- • The domain is the most inclusive taxonomic category; larger than a kingdom  • The three domains are: • Bacteria : kingdom Eubacteria • Archaea,: kingdom Archaebacteria; • Eukarya:Kingdom Protista, Fungi, Plantae, and Animalia.

17. Genus species If these three species belong to the same genus, they are descended from a common ancestor. Felis domestica domestica Domestic Cat Felis Felis leo leo Lion Felis margarita margarita Sand cat`

18. Classification Using Cladograms Cladogram: A diagram that shows the evolutionary relationships among a group of organisms. Derived trait- new traits that show up in a lineage ex. jaws, lungs, mammary glands

19. Modern Evolutionary Classification • Molecular Clocks • A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently. • Comparison reveals more DNA in common, the more recent the common ancestor

20. Terminology • Classification • Assigning organisms to different catagories based on their relationship • Taxonomy • The science of naming organisms • Systematics • Determining evolutionary relationships of organisms • Phylogeny • Evolutionary history

21. Phylogenetic Tree • Shows evolutionary relationships • More historical than cladogram

22. Uniramia Echinodermata Chelicerata Chordata Lophophorates Crustacea Protochordates Annelida Arthropoda Hemichordata Mollusca Other pseudocoelomates Nemertea Platyhelminthes Ctenophora Nematoda Cnidaria Mesozoa Placozoa Sarcomastigophora Ciliophora Porifera Apicomplexa Microspora Myxozoa

23. Birds Mammals Reptile Feathers Amphibian Fur Fish Endothermic Amniotic Egg Four Limbs Vertebrae

24. Monophyletic groups (Clades) • A group of all the descendants of a common ancestor • The common ancestor is in the group • Example: Birds and Reptiles • Ancestor was a bird like reptile

25. Polyphyletic • group that has some similarities • Contains organisms that have not descended from a common ancestor • Based on physical characteristics instead of evolutionary evidence • Example: Flying vertebrates- pterosaurs, birds, mammals

26. Cladogram • Shows Evolutionary relationships of a group of organisms • Each clad (group) share something in common • Ancestral traits are the oldest • Derived traits evolved later

27. Cladogram for Transportation • Wheels are the most ancestral • Wings are the most derived

28. Construct a Cladogram

29. Gorilla • Four limbs • Fur • Lost tail

30. Tiger • Four limbs • Fur • Tail

31. Lizard • Four limbs • Tail

32. Fish • Tail

33. Chimpanzee • Four limbs • Fur • Lost tail

34. Clad With 4 Limbs

35. Clad With Fur

36. Clad With No Tail

37. Characteristics for Constructing Cladogram • Tail is the most ancestral • Four limbs is the oldest derived trait • Fur is a later derived trait • Loss of tail is the most derived trait

38. Gorilla Chimpanzee Tail Lost Fur Four Limbs Tiger Lizard Fish

39. Gorilla Tail? • How do we know the gorilla lost its tail?

40. Human Gorilla’s Vestigial Tail Gorilla

41. The End.