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

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Presentation on theme: "Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth."— Presentation transcript:

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

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

3

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

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 HOW this happens- Pangaea /Continental Drift Landform isolation- river, mountain, water. (ex. Squirrels of N. Grand Canyon) Australia

9 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 Convergent Evolution : Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

10 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.

11 Related This incorrect because crabs and barnacles are actually related

12 12 TRADITIONAL CLASSIFICATION CLADOGRAM AppendagesConical Shells Crab Barnacle Limpet Crab Barnacle Limpet CrustaceansGastropod Molted exoskeleton Segmentation Tiny free-swimming larva Section 18-2 Traditional Classification Versus Cladogram Go to Section:

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

14 Evolutionary Classification  Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities Evolution Classification Evolution Classification : Is the strategy of grouping organisms together based on their evolutionary history.

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

16 Classification Using Cladograms Cladogram Cladogram : A diagram that shows the evolutionary relationships among a group of organisms.

17 Crustaceans Using Cladograms, you can see that crabs and barnacles share similar characteristics because they both molt & are segmented Gastropods Molted Exoskeleton Segmentation Free swimming Larva

18 Crustaceans You can also see that ALL have a free swimming larval stage Gastropods Molted Exoskeleton Segmentation Free swimming Larva

19 Modern Evolutionary Classification  Similarities in DNA and RNA The genes of many organisms show important similarities at the molecular level that can be used as criteria to help determine classification. 19

20 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

21 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

22 Phylogenetic Tree  Shows evolutionary relationships  More historical than cladogram 22

23 23 MyxozoaMyxozoa ArthropodaArthropoda AnnelidaAnnelida MolluscaMollusca LophophoratesLophophorates HemichordataHemichordata ChordataChordata OtherpseudocoelomatesOtherpseudocoelomates NematodaNematoda PoriferaPorifera CtenophoraCtenophora CnidariaCnidaria PlacozoaPlacozoa PlatyhelminthesPlatyhelminthes NemerteaNemertea CiliophoraCiliophora SarcomastigophoraSarcomastigophora MicrosporaMicrospora ApicomplexaApicomplexa MesozoaMesozoa EchinodermataEchinodermata CrustaceaCrustacea ChelicerataChelicerata UniramiaUniramia ProtochordatesProtochordates

24 24 Birds Mammals Reptile Amphibian Fish Four Limbs Amniotic Egg Endothermic Fur Feathers Vertebrae

25 Monophyletic  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

26 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

27 Cladogram  Evolutionary relationship of a group of organisms  Each clad (group) share something in common  Ancestral traits are the oldest  Derived traits evolved later 27

28 Cladogram for Transportation  Wheels are the most ancestral  Wings are the most derived 28

29 Construct a Cladogram 29

30 Gorilla  Four limbs  Fur  Lost tail 30

31 Tiger  Four limbs  Fur  Tail 31

32 Lizard  Four limbs  Tail 32

33 Fish  Tail 33

34 Chimpanzee  Four limbs  Fur  Lost tail 34

35 Clad With 4 Limbs 35

36 Clad With Fur 36

37 Clad With No Tail 37

38 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

39 39 GorillaChimpanzee Tiger Lizard Fish Four Limbs Fur Tail Lost

40 Gorilla Tail?  How do we know the gorilla lost its tail? 40

41 Gorilla’s Vestigial Tail 41 Gorilla Human

42 The End.


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