Biologists classify and organize living things into taxonomic groups to better study the diversity of life in a logical manner. The science of classification is called taxonomy. Carolus Linnaeus is considered the father of taxonomy and made two main contributions - assigning each organism a two-part Latin name called binomial nomenclature and grouping organisms in a hierarchical classification system of kingdom, phylum, class, order, family, genus, and species. Modern classification systems aim to represent evolutionary relationships and lineages of descent rather than just physical characteristics.

2. Finding Order in DiversityChapter 18Page 446

3. Why Classify? (Why Organize?)To study the great diversity of life. Biologists attempt to organize living things into groups in a logical manner that have biological meaning.

4. The science of organizing and classifying is called TAXONOMY. Each life form is given a universally accepted name. (This avoids confusion caused by regional names.)What is the name of this animal?Mountain lion / puma / cougar / pantherFelisconcolor

5. Classification: A Historical PerspectiveAristotle (350 BC) – Noted the need for classification. Distinguished organisms by habitat and means of reproduction [simple and obvious groups]Point – God is orderly and organized and we are created in His image, therefore, it is right for us to be ordered and organized…2. Carolus Linnaeus (1707-1778) – Father of Taxonomy. Two main contributions…

6. 1. Assigned each organism a two-part Latin name. Binomial Nomenclature Part I – Genus (first letter always capitalized) Part II – species (first letter always lowercase) [Canis lupus – gray wolf] [Canisfamiliaris – common dog]-- usually italicized or underlinedLinnaeus focused on two groups of life – Plants and Animals – he contributed 11,000 biological names.

7. 2. Grouped organisms into a hierarchy of categories: Kingdom (large and general) Phylum Class Order Family Genus Species (small and specific)Taxon - a group to which organisms are assigned according to the principles of taxonomy, including species, genus, family, order, class, and phylum

8. Modern ClassificationBiologists now group organisms into categories that represent lines of descent (phylogeny), not just visible physical characteristics.Lines of descent form a family tree diagram called a cladogram. [Cladograms are useful tools that help scientists understand how one lineage branched from another in the course of evolution. A cladogram represents evolutionary relationships among a group of organisms.]

9. Systems of ClassificationThe scientific view of life was simpler in Linnaeus’s time:1. 1700’s  Plants and Animals2. 1800’s  Plants, Animals, and Protists (microbes)

10. 3. R.H. Whittaker (1950’s) – proposed a 5 Kingdom system of classification based on cell type – Eukaryotic vs. Prokaryotic

11. 4. (1990’s) – A Six Kingdom Classification System

12. 4. Carl Woese(most recent – late 1990’s) – Proposed the formation of three domains.