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Modern Evolutionary Classification Notes- Ch. 18.2

Modern Evolutionary Classification Notes- Ch. 18.2. Evolutionary Classification. Modern classification is based on evolutionary theory Phylogeny – study of how orgs are related to each other (their evo relationships)

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Modern Evolutionary Classification Notes- Ch. 18.2

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  1. Modern Evolutionary ClassificationNotes-Ch. 18.2

  2. Evolutionary Classification • Modern classification is based on evolutionary theory • Phylogeny – study of how orgs are related to each other (their evo relationships) • Evolutionary Classification – grouping organisms based on their evolutionary history

  3. Homologous Structures • One way to discover relationships is by comparing anatomical structures (body organs and parts). • Parts that are alike in basic structure and origin in several organisms but are not used for the same reason are called homologous structures. • Ex. All above have the same bones and number, used differently- evidence points to common ancestor.

  4. Cladograms • Certain features shared by different group of organisms are known as “derived characters.” • Derived characters – characteristics that are in recent parts of lineage but not in older members • Used to make cladograms (aka phylogenetic tree) • The more derived characteristics two organisms share, the closer their evolutionary relationship

  5. Sample Evolutionary Tree Small difference Common Ancestor Largest difference Moderate difference Smallest difference Relative Time

  6. Traditional Classification Vs Cladogram Section 18-2 Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva TRADITIONAL CLASSIFICATION CLADOGRAM Go to Section:

  7. Traditional Classification Vs Cladogram Section 18-2 Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva TRADITIONAL CLASSIFICATION CLADOGRAM Go to Section:

  8. DNA & RNA • All living things have it • Compare organisms by genes • More similar = more recent common ancestor

  9. Molecular Clocks • Estimates amount of time since species diverged • Uses mutations as markers • Compare similarities and differences in genes

  10. Quick Lab • Identify the organisms in the table that is the least closely related to the others. • Construct a cladogram of these animals. Do NOT copy the table. • Analysis questions on next slide.

  11. 3. Analysis Questions • What trait separates the least closely related organism from the other animals? • List the animals in your cladogram in order of distance from the least closely related organism. • Explain if your cladogramindicates that lizards and humans share a more recent common ancestor than either does with an earthworm. • Where would you insert a frog if you added it to the cladogram? Explain your answer.

  12. Extra Practice 1. Construct a cladogram for the info above. 2. Three previously unknown vertebrates have been discovered in a rainforest in South America. a. “rat-like creature” b. “iguana-like creature” c. “goldfish-like creature” Place these animals on your cladogram and justify your placement.

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