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Chapter 18 Phylogeny and the Tree of Life

Chapter 18 Phylogeny and the Tree of Life. Phylogeny. Phylon = tribe, geny = genesis or origin The evolutionary history of a species or a group of related species. Phylogeny. Found in the fossil record, molecules and genomes. Systematics.

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Chapter 18 Phylogeny and the Tree of Life

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  1. Chapter 18Phylogeny and the Tree of Life

  2. Phylogeny • Phylon = tribe, geny = genesis or origin • The evolutionary history of a species or a group of related species.

  3. Phylogeny • Found in the fossil record, molecules and genomes.

  4. Systematics • The study of biological diversity and classification. • Uses evidence from the fossil record and other sources to reconstruct phylogeny.

  5. Systematics fuses: 1. Phylogeny- tracing of evolutionary relationships. 2. Taxonomy- the identification and classification of species.

  6. Taxonomy • Modern system developed by Linnaeus in the 18th century.

  7. Linnaeus Taxonomy 1. Binomial Nomenclature – two names for each organism. Ex - Homo sapiens 2. Hierarchical System – arranges life into groups. Ex - Kingdom  Species: List

  8. 7 hierarchical divisions • Kingdom Phylum Class Order Family Genus Species • King Phillip Came Over From Germany Sorry.

  9. Scientific names • Composed of Genus and species. • Written in Latin and shown in italics or underlined.

  10. Goal of Systematics • To have Taxonomy reflect the evolutionary relationships or phylogeny of the organisms.

  11. Phylogenetic Tree • Branching diagram showing evolutionary relationships between organisms. • AKA Cladogram

  12. Phylogenetic tree - Example

  13. Trees show: • Ancestral lineage • Branch points • Length of branch point suggests “time” and degree of closeness.

  14. Phylogenetic tree - Example Branch point Ancestral Lineage

  15. Problem • Not all “likeness” is inherited from a common ancestor. • Problem is of homology vs analogy.

  16. Only one is a cactus

  17. DNA patterns • If similar DNA – more closely related, more recent common ancestor. • If different DNA – less closely related, less recent common ancestor.

  18. Making a Tree • Maximum parsimony – requires fewest DNA base changes. (most simple explanation) • Branch lengths – suggest the closeness of the relationships

  19. 5 Kingdom System • R.H. Whittaker - 1969 • System most widely used, but is changing.

  20. Main Characteristics • Cell Type • Structure • Nutrition Mode

  21. Current Views • Domains – a system of classification that is higher than kingdom.

  22. 3 Domains 1. Bacteria – prokaryotic. 2. Archaea – prokaryotic, but biochemically similar to eukaryotic cells. 3. Eukarya – the traditional eukaryotic cells.

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