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Advanced Biology Chapter 23 Systematics and Phylogenetic Revolution

Advanced Biology Chapter 23 Systematics and Phylogenetic Revolution. Systematics. Systematics is the study of evolutionary relationships Phylogeny is the study of the patterns of relationships among species. Descent with Modification.

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Advanced Biology Chapter 23 Systematics and Phylogenetic Revolution

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  1. Advanced BiologyChapter 23Systematics and Phylogenetic Revolution

  2. Systematics • Systematics is the study of evolutionary relationships • Phylogeny is the study of the patterns of relationships among species

  3. Descent with Modification • Charles Darwin believed that all species had a common ancestor and that they changed over time like the branching on a tree

  4. Cladistics • Method used to show derived characteristics in a phylogenetic pattern • Derived Characteristic - similarities inherited from recent common ancestor (hair in mammals) • Ancestoral Characteristic similarities that were inherited prior to recent common ancestor that other species do not share

  5. Cladograms • Cladograms is a diagram to show a proposed evolutionary relationship between various species • Clade is a group of different species that share a derived characteristic • Separate using an outgrouping • Principle of Parsimony – simplest theory with fewest assumptions

  6. Video on constructing a cladogram http://www.youtube.com/watch?v=46L_2RI1k3k

  7. Terminology • Synapomorpy is a derived trait that is shared by two or more taxa within a clade and recent ancestor • Apomorphy is a derived trait that evolved within a tree • Pleisomorphy is another name for the ancestral characterstic (old trait)

  8. Convergent Evolution aka Evolutionary Reversal

  9. Photo taken by: Craig Pemberton http://www.flickr.com/photos/40154894@N06/3790813865

  10. DNA • Instead of looking at characteristic traits, most scientist are now building phylogenetic trees based on the genetic code

  11. Tree of Life

  12. Classification Paraphyletic group – includes the most recent common ancestor but NOT ALL DESCENDENTS Polyphyletic group – unrelated organisms that does not include the most recent common ancestor of all groups • Classification is how species are placed into groups of hierarchy • Monophyletic group – includes recent common ancestor and all of its decendents

  13. Monophyletic, polyphyletic and paraphyletic

  14. Phylogenetic Species Concept • This is a concept that states that scientists should use evolution as the means of identifying a species instead of the biological species concept which states that a species is able to interbreed and produce viable offspring • Homologous structures come from the same body part such as legs of a horse and dolphins flipper • Homoplastic structures come from a different body part but are similar such as wings of birds and butterflies

  15. Homologous Structures Homplastic Structures

  16. HIV (Human Immunodeficiency Virus) • HIV first detected in 1980s and currently infects more than 33 million people • Middle of the 80s discovered simian immunodeficiency virus (SIV). Found in laboratory monkeys • SIV showed similar characteristics as HIV but with slight differences. • It is now believed that HIV has been around for more than a million years and has been evolving • Use phylogenetic trees to trace HIV pathways

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