Finding Order in Diversity<br />Chapter 18<br />Page 446<br />
Why Classify? (Why Organize?)<br />To study the great diversity of life. <br />Biologists attempt to organize living things into groups in a logical manner that have biological meaning.<br />
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.)<br />What is the name of this animal?<br />Mountain lion / puma / cougar / panther<br />Felisconcolor<br />
Classification: A Historical Perspective<br />Aristotle (350 BC) – Noted the need for classification. Distinguished organisms by habitat and means of reproduction [simple and obvious groups]<br />Point – God is orderly and organized and we are created in His image, therefore, it is right for us to be ordered and organized…<br />2. Carolus Linnaeus (1707-1778) – Father of Taxonomy. Two main contributions…<br />
1. Assigned each organism a two-part Latin name. Binomial Nomenclature<br /> Part I – Genus (first letter always capitalized)<br /> Part II – species (first letter always lowercase)<br /> [Canis lupus – gray wolf]<br /> [Canisfamiliaris – common dog]<br />-- usually italicized or underlined<br />Linnaeus focused on two groups of life – Plants and Animals – he contributed 11,000 biological names.<br />
2. Grouped organisms into a hierarchy of categories:<br /> Kingdom (large and general)<br /> Phylum<br /> Class<br /> Order<br /> Family<br /> Genus<br /> Species (small and specific)<br />Taxon - a group to which organisms are assigned according to the principles of taxonomy, including species, genus, family, order, class, and phylum<br />
Modern Classification<br />Biologists now group organisms into categories that represent lines of descent (phylogeny), not just visible physical characteristics.<br />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.]<br />
Systems of Classification<br />The scientific view of life was simpler in Linnaeus’s time:<br />1. 1700’s Plants and Animals<br />2. 1800’s Plants, Animals, and Protists (microbes)<br />
3. R.H. Whittaker (1950’s) – proposed a 5 Kingdom system of classification based on cell type – Eukaryotic vs. Prokaryotic<br />
4. (1990’s) – A Six Kingdom Classification System<br />
4. Carl Woese(most recent – late 1990’s) – Proposed the formation of three domains.<br />
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