1. Unit 6: Classification and Diversity Classification of Living Things Scientists estimate that there are between 3 million and 100 million species of organisms on Earth. Taxonomists Taxonomists--biologists who specialize in identifying and classifying life on our planet--have named approximately 1.7 million species so far. 13,000 Each year, about 13,000 new species are added to the list of known organisms.new species So, how do scientists classify (organize) all these millions of species?

2. Unit 6: Classification and Diversity Aristotle classified organisms as plants or animals. Then he grouped animals based on how they moved: swim/ fly/ walk This became a problem for animals that walk and fly. Which of Arsitotle’s groups do they go into?

3. Unit 6: Classification and Diversity KEY CONCEPT Organisms can be classified based on physical similarities.

4. Unit 6: Classification and Diversity Linnaeus developed the scientific naming system still used today. Taxonomy is the science of naming and classifying organisms. A taxon is a group of organisms in a classification system. White oak: Quercus alba

5. Unit 6: Classification and Diversity Binomial nomenclature is a two-part scientific naming system. –uses Latin words –scientific names always written in italics –two parts are the genus name and species descriptor

6. Unit 6: Classification and Diversity A genus includes one or more physically similar species. –Species in the same genus are thought to be closely related. –Genus name is always capitalized. A species descriptor is the second part of a scientific name. –always lowercase –always follows genus name; never written alone Tyto alba

7. Unit 6: Classification and Diversity Scientific names help scientists to communicate. –Some species have very similar common names. –Some species have many common names.

8. Unit 6: Classification and Diversity Linnaeus’ classification system has seven levels. Each level is included in the level above it. Levels get increasingly specific from kingdom to species.

9. Unit 6: Classification and Diversity The Linnaean classification system has limitations. Linnaeus taxonomy doesn’t account for DNA evidence. –The technology didn’t exist during Linneaus’ time. –Linnaean system based only on physical similarities.

10. Unit 6: Classification and Diversity DNA data may confirm classification based on physical similarities. DNA data may lead scientists to propose a new classification. DNA evidence reveals species’ relatedness. DNA is usually given the last word by scientists.

11. Unit 6: Classification and Diversity KEY CONCEPT The current tree of life has three domains.

12. Unit 6: Classification and Diversity Classification is always a work in progress. The tree of life shows our most current understanding. New discoveries can lead to changes in classification. –Until 1866: only two kingdoms, Animalia and Plantae Animalia Plantae

13. Unit 6: Classification and Diversity Classification is always a work in progress. The tree of life shows our most current understanding. New discoveries can lead to changes in classification. –Until 1866: only two kingdoms, Animalia and Plantae –1866: all single-celled organisms moved to kingdom Protista Animalia Protista Plantae

14. Unit 6: Classification and Diversity Classification is always a work in progress. The tree of life shows our most current understanding. New discoveries can lead to changes in classification. –Until 1866: only two kingdoms, Animalia and Plantae –1938: prokaryotes moved to kingdom Monera –1866: all single-celled organisms moved to kingdom Protista Animalia Protista Plantae Monera

15. Unit 6: Classification and Diversity The tree of life shows our most current understanding. New discoveries can lead to changes in classification. –Until 1866: only two kingdoms, Animalia and Plantae Classification is always a work in progress. –1938: prokaryotes moved to kingdom Monera –1866: all single-celled organisms moved to kingdom Protista Monera –1959: fungi moved to own kingdom Fungi Protista Plantae Animalia

16. Unit 6: Classification and Diversity The tree of life shows our most current understanding. New discoveries can lead to changes in classification. –Until 1866: only two kingdoms, Animalia and Plantae Classification is always a work in progress. –1938: prokaryotes moved to kingdom Monera –1866: all single-celled organisms moved to kingdom Protista –1959: fungi moved to own kingdom –1977: kingdom Monera split into kingdoms Bacteria and Archaea Animalia Protista Fungi Plantae Archea Bacteria

17. Unit 6: Classification and Diversity The three domains in the tree of life are Bacteria, Archaea, and Eukarya. Domains are above the kingdom level.

18. Unit 6: Classification and Diversity Nuclear membrane similarities differences Eukaryotes Prokaryotes Remember the similarities and differences between Eukaryotes and Prokaryotes.

19. Unit 6: Classification and Diversity Domain Bacteria includes prokaryotes in the kingdom Bacteria. –one of largest groups on Earth –classified by shape, need for oxygen, and diseases caused

20. Unit 6: Classification and Diversity –known for living in extreme environments Domain Archaea includes prokaryotes in the kingdom Archaea. –cell walls chemically different from bacteria

21. Unit 6: Classification and Diversity Domain Eukarya includes all eukaryotes. –kingdom Protista

22. Unit 6: Classification and Diversity Domain Eukarya includes all eukaryotes. –kingdom Protista –kingdom Plantae

23. Unit 6: Classification and Diversity Domain Eukarya includes all eukaryotes. –kingdom Protista –kingdom Plantae –kingdom Fungi

24. Unit 6: Classification and Diversity Domain Eukarya includes all eukaryotes. –kingdom Protista –kingdom Plantae –kingdom Fungi –kingdom Animalia

25. Unit 6: Classification and Diversity A species is defined as organisms that are so alike (from the same Genus) that they can produce fertile offspring. Two different species may produce offspring, but it will be infertile and unable to produce new offspring. The new animal is a hybrid of two species. Tiger x lion= Liger Polar Bear x Grizzly Bear= Grolar Bear Zebroid= zebra x animal from Equis (x horse= zorse, x donkey= zonkey, etc.)