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Exploring Systematics: Classifying Organisms and Rocks for Fundamental Science Databases

Learn about the importance of classifying organisms into groups, the goals of classification, and different schools of classification such as Traditional Taxonomy and Cladistics. Discover how classification is crucial in understanding evolutionary relationships. Visit the provided links to explore evolutionary trees and cladograms.

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Exploring Systematics: Classifying Organisms and Rocks for Fundamental Science Databases

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  1. Systematics Classifying organisms into groups

  2. Why classify? • To create the fundamental database of the science • Analogy - classification systems for rocks • Big difference - • Rocks are on a continuum of composition • Organisms fall into discrete groups (species) • So geological classification tends to be graphical and biological is hierarchal

  3. http://www.newworldencyclopedia.org/entry /File:Hominoid_taxonomy_6.png http://www.geologycafe.com/images/igneous_rocks.jpg

  4. Goals of classification • Make morphologic groups • This is what Linneaus was trying to do in the 1700’s • Represent evolutionary relationships • These two goals are not always compatible

  5. Schools of classification • Traditional taxonomy • Phenetics • Cladistics

  6. Traditional • Original goal: produce morphologic groups • New goal: represent evolutionary relationships, produce “natural groups” • Find patterns of ancestry • Methodology: analyze “important” characters • Product: evolutionary trees • Requires expertise - only an expert recognizes the important characters • How is it objective? • How is it subjective? • Challenges: convergent evolution

  7. Cladistics • Goal: to construct and test evolutionary hypotheses • Find sister groups, not ancestry • Sister groups are evolutionary related, but it makes no statement about descent • Methodology: analyze derived characters • Characters that mark a change from the lineage that led to this organism • Product: cladogram

  8. Cladistics, cont. • Requires expertise to recognize derived characters • Challenge: blows up some recognized groups

  9. Evolutionary tree – what are the axes? http://darwiniana.org/famtree3b.gif

  10. Cladograms – what are the axes? Why aren’t they the same? http://tolweb.org/tree/ToLimages/ cladogram_parallel_evo.250a.jpg https://www.sciencemag.org/content/340/6129/ 1233062/F1.large.jpg

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