Taxonomy is the science of classifying living things. Organisms are grouped based on similarities into a hierarchical system of categories ranging from broad Kingdoms to specific Species. The modern system has three Domains - Archaea, Bacteria, and Eukarya - reflecting evolutionary relationships determined by molecular analysis. Carolus Linnaeus developed the binomial nomenclature system still used today, assigning every species a two-part scientific name describing its Genus and differentiating species. Classification systems continue evolving to best represent the evolutionary history and relationships between all forms of life.

1. taks-AHN-uh-mee Sorting out the whatchamacallits

2. Definition of Terms Taxonomy: the science of identifying, classifying, and naming living things. Classification: the arrangement of organisms into orderly groups based on their similarities.

3. Why Classify? Humans have an innate need to seek order in their surroundings. Order helps us understand how the world works. We can communicate better when everyone knows what we are talking about.

4. History of Classification Aristotle (384-322 B.C.) had a simple method: Plants and Animals Animals lived on land, in water, or in air Plants had three different types of stems This worked until explorers found many new organisms that didn’t fit his system. Common names often varied from region to region or were inaccurate (ex: Jellyfish)

5. History of Classification Carolus Linnaeus (1707-1778) developed a system with hierarchical categories. Based on shared physical characteristics. Uses seven levels of organization The largest is Kingdom and the most specific is Species .

8. Classification Hierarchy Kingdom Phylum (Division….for plants) Class Order Family Genus Species

9. Classification Hierarchy K P C O F G S

10. Binomial Nomenclature Binomial nomenclature : bi =two nom =name Always in Latin. Why? Latin is a universal language. Species name (scientific name) Always in this form: Genus species identifier Species identifier is often descriptive, geographical, or named after someone

11. Binomial Nomenclature Additional levels of classification beyond Genus and Species include: Varieties : PLANTS with slightly different qualities Subspecies : ANIMALS in different geographical regions

12. Binomial Nomenclature Prunus persica Variety: Nectarine Prunus persica Variety: Peach

13. Binomial Nomenclature Terrapene carolina Common Eastern Box Turtle Terrapene carolina triungui Has three toes instead of four on back feet.

14. Modern Taxonomy Phylogeny : The evolutionary history of an organism A Phylogeny tree diagram shows the relationship of organisms. Uses the same evidence used by evolutionary biologists: Fossil Record Comparing structures Embryo development DNA

17. The Six Kingdom System Kingdom Archaebacteria “ archae” is Greek for ancient Unicelluler with unique biochemical properties Unique gene sequences Live in extreme environments like hotsprings, sea vents

18. The Six Kingdom System Kingdom Eubacteria “ eu” means true Mostly aerobic, but some are anaerobic Affect the lives of humans in many ways Rapid reproduction allows evolutionary response to surroundings

19. The Six Kingdom System Kingdom Protista Mostly single-celled eukaryotic organisms Contains organisms that “don’t fit” into other kingdoms Share aspects of plant and animal kingdom- feed on other organisms but may also use photosynthesis (ex: Euglena)

20. The Six Kingdom System Kingdom Fungi All fungi absorb nutrients from their surroundings, nature’s recyclers Molecularly speaking they are closer to animals then to plants (Chitin) Often work in symbiosis with plants to provide nutrients or protection from disease

21. The Six Kingdom System Kingdom Plantae Nearly all are autotrophic eukaryotes (PHOTOSYNTHESIS) Have a sexual cycle based on meiosis Most live on land

22. The Six Kingdom System Kingdom Animalia Heterotrophic multicellular eukaryotes Have a sexual cycle based on meiosis Symmetrical body organization Most have some mobility

24. The Three Domain System Based on molecular work with Ribosomal RNA All organisms tested fall into one of three distinct Domains Introduced in 1990 by Carl Woese (discovered Archeabacteria)

25. The Three Domain System Domain Archaea The same members as Kingdom Archaebacteria Domain Bacteria The same members as Kingdom Eubacteria Domain Eukarya Consists of Kingdoms Protista, Plantae, Fungi, and Animalia