1. What is a Dichotomous Key?

3. Classification Chapter 18 Ridgewood High School scasatelli@ridgewood.k12.nj.us

4. Introduction The earth contains millions of different species. Species: a group of organisms that share similar characteristics and can breed to produce fertile offspring. Bulldog + Poodle Tiger + Liger

5. Why Classify? In order to communicate effectively with other cultures organisms must have a system of classification to identify certain species. Taxonomy- is the study of classifying organisms by their characteristics. Naming

6. Binomial Nomenclature In order to eliminate confusion scientist in the 1800’s came up with a naming system. Binomial Nomenclature Homo sapiens All words are in a common language called Latin What is this?

7. Binomial Nomenclature Cont. Homo sapien The first word Homo is the genus of the species. The second word is the species identifier in this case sapien. Two species may have the same genus but different species identifier. Tursiops truncatus Tursiops australis Tursiops aduncus

8. Linnaeus’s System of Classification Linnaeus devised a 7 level system of classfication. Largest to Smallest Kingdom Phylum Class Order Family Genus Species King Philip Carved Out Family Grave Stones

9. Linnaeus’s System of Classification Cont. As species share certain characteristics they may share certain levels of organization. As they differ so will the levels of organization. Ursus maritimus Ursus arctos Ailuropoda melanoleuca

10. Linnaeus Cont. Great Pic on page 450 figure 18-5

11. 18.2 Modern Evolutionary Classification Linnaeus’s system of classification was based on physical characteristics which has it’s limitations Wolf and Dog Dolphin and Shark

12. Evolutionary Classification Phylogeny: the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms. Cladogram: a diagram that shows relatedness among species by using derived characters. Derived Character: a characteristic that appears in recent parts of lineage but not older. Evolutionary Classification: the strategy of grouping organisms based on their evolutionary history

13. Phylogeny vs. Cladogram

14. Cladograms Cont. Derived Characters: are characteristics that appears in recent parts of lineage but not older members. Ex. Wings, Jaws, Fins, Arms

15. Similarities in DNA and RNA The DNA of many organisms show important similarities at the molecular level. Can be used to determine relatedness among species.

16. DNA Cont. Traditionally the African and American vulture were thought to be directly related. Through DNA analysis it is revealed that the American vulture resembles the stork more closely Both urinate on their legs to keep cool African Vulture  Above: American Vulture Stork 

17. Do Now: What is Taxonomy? Taxonomy- is the study of classifying organisms by their characteristics. What are Taxa? Taxa- a specific level within a classification What are the levels of Classification today? *Domain*, Kingdom, Phylum, Class, Order, Family, Genius, Species

18. 18.3 Kingdoms and Domains Linnaeus’s system had two kingdoms. Plants and Animals What Kingdom would Linnaeus place photosynthetic bacteria?

19. Modern Six Kingdom System Animalia Plantae Fungi Protista Eubacteria Archaebacteria Unicellular Yeast is the only fungus that is unicellular

20. 3 Domain System Eukarya: (all eukaryotes) Animalia, Plantae, Fungi and Protista Bacteria: Eubacteria Archae: Archaebacteria

21. Classification in a nutshell