3 - Biol. 1001 Spring 2008 (B. Fall), Class notes, topic...

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Biol. 1001 Spring 2008 (B. Fall), Class notes, topic #3—Evolutionary relationships and classification. Preparation: complete the reading assignment in your text (Freeman, Biological Science, 2 nd ed.): pp. 5-10, 556-561, 614 Learning objectives: 1. Appreciate what systematics is and why it is an important branch of biology. 2. Become familiar with Linnaean classification categories and binomial nomenclature. 3. Understand the relationship between common descent and a natural, hierarchical classification system. 4. Appreciate some methods used by scientists to reconstruct evolutionary history. 5. Learn how to “read” a phylogenetic tree. 6. Understand that cladistic classification reflects phylogeny and why this is preferred. 7. Understand the basic structure of the tree of life, with three broad branches (domains); distinguish prokaryotes from eukaryotes. Notes: I. Classification A. There are nearly 2 million described living species on Earth; probably many times that number are undiscovered. To help make such bewildering diversity more understandable, humans group or categorize them. Early classifications were devised when species were considered fixed, unchanging. B. Darwin’s idea that living species are descended with modification from pre-existing ones, forming a “tree” with “branches” and “twigs” has been incorporated into a modification of one of these—a nested hierarchy. II. Systematics is the study of the relationships among organisms, and includes taxonomy (the practice of naming and classifying them). A. A goal of modern biological classification is to reflect evolutionary genealogy ( phylogeny , or the evolutionary history of a taxon)—thus there is historical information in such a classification. A taxon (pl., taxa) is a named group of related organisms, at any taxonomic category level. Dogs and wolves (genus Canis ) and birds (class Aves) are two examples of taxa. B. Carolus Linneaus (1707-1778) is the father of modern classification ( Systema Naturae ). He introduced the concept of binomial nomenclature (genus + specific epithet). Linneaus was a creationist, not an evolutionist (he classified for the “greater glory of God”), yet his hierarchical system lent itself well to an evolutionary framework. C. Some rules of binomial nomenclature: Latin (or Latinized); italicize; capitalize genus, not specific epithet; name unique within kingdom; example, Homo sapiens (modern humans). D.
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This note was uploaded on 04/21/2008 for the course BIOL 1001 taught by Professor Fall during the Spring '08 term at Minnesota.

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3 - Biol. 1001 Spring 2008 (B. Fall), Class notes, topic...

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