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Chapter 15- Tracing Evolutionary History

Chapter 15- Tracing Evolutionary History

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Chapter 15- Tracing Evolutionary History

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  1. “evo-devo” Analogy Binomial nomenclature Clades Cladistic analysis Class Continental drift Convergent evolution Derived characters Exaptation Family Five-kingdom system Fossil record Genus Geologic time scale Kingdom Macroevolution Molecular clock Order Paedomorphosis Parsimony Phylogenetic trees Phylogeny Phylum Plate tectonics Radiometric dating Species Three-domain system Chapter 15- Tracing Evolutionary History

  2. The fossil record • Shows macroevolution • Major changes in the history of life on Earth • Gives geologic time scale • Eras, periods, separated by extinctions • Radiometric dating- calculates fossil age • Using radioactive isotopes (C for fossils younger than 50,000yrs old)

  3. Mass extinctions • Followed by periods of mass diversification • Due to available resources (niches, space, lack of predators) • Key adaptations allow some species to grow after extinction • Exaptation- a structure that evolved in 1 context and is later adapted for another function • Bird feathers- 1st for temp regulation; later for flight

  4. Continental drift • Plays a role in macroevolution • Slow movement of continents due to movement of Earth’s crust • Explains distribution of ancient species • Plate tectonics- forces that move crust

  5. Things to consider: • Evolution is NOT trying to reach a goal • Results from changes in the environment • Causes some to survive and others not to • Gradual evolutionary changes come from genetic changes • “evo-devo”- field that studies how slight genetic variance can magnify morphological differences • Paedomorphosis- adults keeping juvenile features

  6. Phylogeny • Evolutionary history of a group of organisms • Represented by phylogenetic trees

  7. Classification • Taxonomy- the study of naming and classifying species and groups of species • Linnaeus system assigned 2 part latinized names • Ex: Homo sapiens • Kingdom-Phylum-Class-Order-Family-Genus-Species • Kings – Play – Cards – On – Fat – Green – Stools • In order to classify an organism scientists must use all available evidence to classify properly

  8. Classification and phylogeny

  9. Homology vs. Analogy • Homology- structures may look and function differently but they have evolved from the same structure • Indicates common ancestor • Analogy- similarities due to convergence • Convergent evolution- species from different evolutionary branches come to resemble one another due to living in similar environments

  10. Now- • Molecular biology helps classify organisms • Protein comparisons- amino acid sequencing • DNA and RNA comparisons- • mtDNA – compares closely related species, because it mutates quickly • rDNA- changes slowly, used to trace early branching • Molecular clock- evolutionary timing method based on genes that evolve at constant rates

  11. Cladistic Analysis • Atudies evolutionary history of clades (groups consisting of ancestor and all of its descendents) • New traits that arise – derived characters • Phylogenetic tree based on onset of derived characters = cladogram • Parsimony- quest for simplest explanation of observed phenomena

  12. 5 Kingdom vs. 3 Domain • Pictures in textbook show where groups in each fit into the systems pg 312 • Always up for research and debate