2. What we need to learn  How and why organisms are hierarchically classified and based on evolutionary relationships  Learn the reasons for changes in how organisms are classified  Learn the distinguishing characteristics of the domains and kingdoms of living organisms

3. Classifying Organisms  One branch of biology investigates biodiversity  The variety of organisms considered at all levels from populations to ecosystems  Every year scientists find new species and try to classify them in a meaningful way This species has scales and a stinky tongue to catch ants What species would you group this with?

4. Taxonomy  The science of describing, naming, and classifying organisms is called  Taxonomy  Any particular group within a taxonomic system is called a  Taxon

5. Taxonomy  Early work to classify organisms only looked at their life on land or in water  As more species were named, this system became inadequate  Common names were widely used but ran into issues  Some common names don’t truly identify the species

6. The Linnaean System  Carolus Linnaeus developed a system to categorize according to form and structure

7. Levels of Classification  The modern version of Linnaeu’s system  Binomial Nomenclature  Scientific name  Latin  Starts with with genus name  Followed by species identifier  Homo sapiens  Homo-genus  Sapiens-species

8. Levels of classification  Name of species is often very descriptive  Always capitalize first name, lower case second. ALWAYS italicize the names  Subspecies names are often needed  When the same species lives in different geographic areas  Terrapene carolina triunui is a subspecies of Terrapene carolina

10. Phylogenetics  We have already learned this  Phylogenetic trees? Remember?  Phylogenetics  The analysis of the evolutionary or ancestral relationships among taxa

11. Evidence of Shared Ancestry  Remember homologous and analogous structures?  YOU BETTER!  Systematics use homologous structures  Analogous structures and misidentify species  Pangolins and dogs have similar jaw structures  We therefore classify them with dogs  If we classified them based on their scales, what would we classify them with?

12. Cladistics  Cladistics-a system of phylogenetic analysis that uses shared and derived characteristics as the only criteria for grouping taxa  Shared characteristic- a feature that all members of a group have in common  Hair in mammals  Feathers in birds  Derived characteristics- features that evolved only within the group under consideration

13. Cladistics  Clade- the group of organisms that includes an ancestor plus all its descendants  Cladograms-diagrams that show clades and characteristics

15. Three Domains of Life  Domain Bacteria  Small single celled prokaryotic organisms  Have a cell wall, plasma membrane, cytoplasm that lacks complex organelles  Reproduce by cellular fission  No membrane bound DNA, therefore no nucleus

16. Three Domains of Life  Domain Archea  Consists of prokaryotes  Distinctive cell membranes  Some are autotrophic, and produce food by chemosynthesis  Some produce flammable gases, such as methane  Many inhabit harsh environments  Scientists think archea were among the earliest organisms on Earth  Archaea and bacteria have possible coevolved

17. Three Domains of Life  Domain Eukarya  Most familiar group  Consists of eukaryotic organisms  Large cells that have true nucleus and complex cellular organelles  Plants  Animals

18. The Six Kingdoms  Eubacteria  True bacteria

19. The Six Kingdoms  Archaebacteria  Literally means “ancient bacteria”  So different from bacteria now, scientists only use “ archaea” to name them

20. The Six Kingdoms  Protista  First of 4 eukaryotes  Called protists  Defined as those eukaryotes that are not plants, animals, or fungi  Most are unicellular  Scientists actually think the kingdom “Protista” is no longer useful. Most protista are not related to each other  Amoebas and paramecia  Some seaweed and molds

21. The Six Kingdoms  Fungi  Eukaryotic  Heterotrophic  Unicellular, multicellular  Fungi absorb nutrients rather than ingest them  70,000 species of fungi

22. The Six Kingdoms  Plantae  Eukaryotic  Multicellular  Besides some parasitic plants, most are autotrophic  Use photosynthesis as a source of energy  Develop from embryos  Most live on land  Mosses, ferns, flowering plants

23. The Six Kingdoms  Animalia  Eukaryotic  Multicellular  Heterotrophic  Develop from embryos  Symmetrical body organization  Move around their environment to find and capture food