1. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies How We Classify Organisms Chapter 16 Copyright © McGraw-Hill Companies Permission required for reproduction or display

2. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Classification of Organisms Classification - Multilevel grouping of individuals.  Organisms first classified by Aristotle over 2,000 years ago. - Eventually groups started to be formed and referred to as genera (singular, genus).  Starting in Middle Ages, names began to be systematically written down using Latin.

3. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Classification of Organisms Classification scheme of the Middle Ages (polynomial system) was used replaced with a binomial system by Linnaeus about 250 years ago.  Polynomial - Strings of Latin words and phrases containing up to 12 words.  Binomial - Two-part name for each species.

4. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Species Names Taxa - Group of organisms at a particular level in a classification system (Taxonomy). By convention:  First word of binomial name is genus and is always capitalized.  Second word refers to particular species and is not capitalized. - Together form Scientific name, written in italics.

5. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Taxonomic Hierarchy Kingdom Phylum Class Order Family Genus Species Kindly Pay Cash Or Furnish Good Security. King Philip Came Over From Germany Saturday.

6. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies The Taxonomic Hierarchy

7. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies What Is A Species Biological Species Concept - Two organisms that cannot interbreed and produce fertile offspring are labeled different species.  Useful in species that regularly outcross.  Irrelevant for asexual species. Biologists generally agree species delineation based on similarity of morphological features and ecology.

8. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies What Is A Species Evolutionary Species Concept - Single lineage of populations that maintains its distinctive identity from other such lineages.  Applicable to both sexual and asexual reproduction. How Many Species Are There?  1.5 million described and named.  Estimated 10 million total. - Most tropical - 15% marine

9. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Evolutionary Classifications Systematics - Reconstruction and study of evolutionary trees (Phylogenetic trees).  Clade - Organisms related by descent.  Cladistics - Constructing phylogeny according to similarities derived from common ancestor.  Produce branching cladogram.  Compare outgroup (different organism) to the ingroup. Cladogram

10. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Evolutionary Classifications Traditional Taxonomy  Taxa are assigned based on a vast amount of information about the morphology and biology of the organism gathered over a long period of time. - Knowledgeable weighting of characters according to their biological significance.

11. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

12. The Kingdoms of Life Most Biologists use a six-kingdom system.  Animalia  Plantae  Fungi  Protista  Archaebacteria  Eubacteria Domains - Taxonomic level above kingdoms.

13. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Archaea Share key characteristics:  Cells wall lack peptidoglycan.  Possess unusual lipids and ribosomal RNA. Three General Categories  Methanogens - Obtain energy using hydrogen gas to reduce carbon dioxide to methane gas.  Extremophiles - Grow under extreme conditions. - Thermophiles - Heat - Halophiles - Salt - Pressure –Tolerant  Nonextreme Archaebacteria - Grow in same environment as eubacteria.

14. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Bacteria Most abundant organisms on earth. Most taxonomists recognize 12-15 major groups. Copyright © McGraw-Hill Companies Permission required for reproduction or display

15. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Eukarya Appear in fossil record only about 1.5 billion years ago. Complex cellular organization.  Protists, Fungi, Plants, and Animals are well-defined evolutionary groups. - Largely multicellular - Diversity among protists is much greater than within or between Fungi, Plants, and Animals.

16. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Eukarya With few exceptions, all modern eukaryotic cells possess energy-producing organelles (Mitochondria).  Some protist phyla have also acquired chloroplasts and are photosynthetic. - Mitochondria and chloroplasts are both believed to have entered early eukaryotic cells by endosymbiosis.

17. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Eukarya Key Characteristics  Multicellularity - Activities of individual cells are coordinated and the cells themselves are in contact.  Sexuality - Alternate between syngamy and meiosis. Eukaryotic Life Cycles  Zygotic Meiosis - Zygote only diploid cell.

18. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Domain Eukarya  Sporic Meiosis - Zygote is first cell of the multicellular diploid phase. Gametic Meiosis - Gametes are the only haploid cells.

19. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Viruses: A Special Case Viruses do not satisfy the basic criteria of life, thus are not living organisms.  Appear to be fragments of nucleic acids originally derived from genome of a living cell. - Infect organisms at all taxonomic levels.

20. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Copyright © McGraw-Hill Companies Permission required for reproduction or display