The Development of Modern Taxonomy

1. The Development ofModern Taxonomy Mr.G.Burgess 2004

2. Why Taxonomy? • Taxonomy is the branch of biology that is responsible for the naming and classification of organisms. • There are millions of organisms on our planet; from several microns to several meters in length. • Naming of organisms allows scientists to place the organisms into groups based on similarities.

3. Taxonomy in the beginning 4th century BC-Greek philosophers - Aristotle studied animals. • Aristotle, classified organisms by where they lived; air-dwellers, land-dwellers, water-dwellers • Theophrastus studied plants • Theophrastus classified plants by stem structure; woody stems, soft stems, shrubs with many woody stems, and trees. • However, as the number of classified organisms grew, these methods of classification became cumbersome.

4. New beginning • Technological advances made the classifications systems of the philosophers obsolete. • Development of the microscope and refining of lenses enabled scientists to begin examining microscopic life. • A new way of categorizing organisms was needed.

5. John Ray • 1600’s, English naturalist • Identified >18000 different plants. • Used the term species to identify each group of organisms that were structurally similar and were able to pass their characteristics on to offspring.

6. Carolus Linnaeus • The father of taxonomy • Also classified organisms by structural similarities • Changed the way organisms were named. • Organisms were originally given lengthy Latin names • Linnaeus shortened these by using a 2 name system for organisms.

7. Binomial Nomenclature • System of using two names for each organism. • The term genus had been used since Aristotle to describe groups of organisms with similarities and John Ray had used the term species. • Linnaeus used both terms for binomial nomenclature so that scientists could all know what plant / animal was being discussed.

8. Binomial Nomenclature (con’t) • The system for naming was as follows. • All names are comprised of 2 names; genus, species • When writing the names; always capitalize the genus and leave the species small lettered. • Underline both words when in print or put an ‘sp’ after the species name. When typed, the names are italicized.

9. Modern Classification • With the development of the theory of evolution, scientists began visualizing more and more similarities between organisms and developed a classification scheme that began with the species(individual) and ended with the Kingdoms(very large sets of organisms with commonalities).

10. **As the classification group gets SMALLER, the number of similarities between its members gets LARGER. 1. Structural similarities: the look of the organism 2. Cellular similarities: similar organelles 3. Biochemical similarities: similar chemical products (ie. Blood chemistry determines ancestry) 4. Similar embryologic development 5. Genetic similarities: similar number of chromosomes and inherited traits.

11. Dichotomous Key • Tool used to identify organisms • Usually a list of paired questions that describe the structures found on the organisms.

12. Bibliography • johnray.gif, http://www.strangescience.net/biopics/johnray.gif, April 6, 2004. • linnaeussmall.jpg, http://www.ucmp.berkeley.edu/history/linnaeus.html, University of Berkley Museum of Paleontology, April 6, 2004 • Biology the stuudy of life, rervised 3rd edition, W.D.Schraer, and H.J.Stoltze, 1990. Chapter 6 pp.90-102. • Wikipedia the free encyclopedia, http://en.wikipedia.org, April 6, 2004 • Taxonomy:Classifying Life, users.rcn.com/.../BiologyPages/ T/Taxonomy.html, April 6, 2004. • Image1.gif, http://www.csuchico.edu/~mw97/Biol_142/Image1.gif, April 7, 2004.