1. Taxonomy & Classification
Organization of Life
Taxonomy & Classification

2. Vocabulary
Classification: grouping objects or info based on similarities
Biodiversity: the variety of organisms considered at all levels from populations to ecosystems
Taxonomy: science of describing, naming, and classifying organisms
Taxon (plural taxa): any particular group w/in a taxonomic system
Binomial nomenclature: system of 2 part names for organisms consisting of genus and species

3. More Vocab
Dichotomous key: key for the identification of organisms based on a series of choices between alternative characteristics
Unicellular: organisms consisting of a single cell
Multicellular: organisms consisting of more than one cell

4. More Vocab:
Autotroph: an organism that produces its own nutrients from inorganic substances or from the environment instead of consuming other organisms
Heterotroph: organism that obtains organic food molecules by eating other organisms or their byproducts and that cannot synthesize organic compounds from inorganic molecules
Cladistics: a phylogenetic classification system that uses shared derived characteristics and ancestry as the sole criterion for grouping taxa
Phylogeny: evolutionary history of a species or taxon

5. History of Classification
Why do we classify: to better understand the organisms that we coexist with
How do we classify: based on similarities
Taxonomy: science of grouping and naming organisms based on their similarities and differences

6. History of Classification
Aristotle ( B.C.)
Developed the 1st widely used system of classification
Classified organisms into plants and animals
Subdivided plants into herbs, shrubs, trees based on size and structure
Subdivided animals by characteristics such as habitat & physical differences
Did not use evolutionary history as a basis for classification

7. History of Classification
Aristotle classified the organisms below into the same category, make sense?

8. History of Classification
Linnaeus ( )
System still used today
Based on physical and structural similarities in organisms
His groupings revealed relationships b/t organisms
Grouped organisms into hierarchical categories, the lower the level the more closely relate the organisms in it
Used binomial nomenclature to name organisms

9. History of Classification
Binomial Nomenclature
2 word naming system, italicized or underlined
1st word: genus of the organism, 1st letter upper case
2nd word: species of the organism
This sometimes describes a specific characteristic of the species that denotes it from others of the same genus
i.e.: homo sapiens: homo = genus, sapiens = wise which distinguishes humans from other organisms in the homo genus

10. History of Classification
Modern Classification
Builds on Linnaeus’s work
Tries to use evolutionary relationships
Compares internal and external characteristics, geography & genetics

11. Taxonomy Science of describing, naming and classifying organisms
Taxon: group w/in a taxonomic system
Taxa are bases on the closeness of the organisms in them

12. Taxonomy
Modern levels of classification, from broadest (organisms w/in share the least similarities, to the narrowest, organisms are extremely similar)
(highest level )Domain  kingdom  phylum  class  order  family  genus  species (lowest level)
From the highest, each level includes all of the organisms grouped in the taxa below it

13. Modern Taxonomy

14. Taxa: Kingdom 6 different kingdoms
Organisms placed in kingdoms based on differences primarily in:
Cellular structures
Methods of obtaining energy

15. Kingdom Eubacteria “true bacteria”
Prokaryotic – lack nucleus and other organelles
Cell wall w/ peptidoglycans & cell membrane w/ fatty acids
Unicellular
Heterotrophic and autotrophic by chemosynthesis or photosynthesis
i.e.: salmonella, streptococci, cyanobacteria

16. Kingdom Eubacteria

17. Kingdom Archaebacteria
“ancient bacteria”
Prokaryotic
Cell wall & cell membrane w/ hydrocarbons in addition to fatty acids
Unicellular
Heterotrophic & autotrophic by chemosynthesis
i.e.: Methanosarcina, Halobacterium

18. Kingdom Archeabacteria

19. Kingdom Protista (aka Protists)
Eukaryotes that aren’t plants, animals, fungi
Eukaryotic – have nucleus & organelles
Cell wall w/ cellulose & cell membrane w/ fatty acids
Mostly unicellular, multicellular forms lack cellular organization
Autotrophic by photosynthesis, some heterotrophic by phagocytosis, some both
i.e. unicellular: amoebas & paramecia
i.e. multicellular: some seaweeds & molds

20. Kingdom Protista

21. Kingdom Fungi Eukaryotic
Cell wall w/ chitin & cell membrane w/ fatty acids
Unicellular & multicellular
Heterotrophic by secreting digestive enzymes, absorb nutrients, don’t ingest
About 70,000 species
i.e. mushrooms, puffballs, rusts, smuts

22. Kingdom Fungi

23. Kingdom Plantae Eukaryotic
Cell wall w/ cellulose & cell membrane w/ fatty acids
Multicellular & develop from embryos
Autotrophic by photosynthesis, few parasitic
i.e. mosses, ferns, conifers, flowering plants

24. Kingdom Plantae

25. Kingdom Animalia Eukaryotic Cell membrane w/ fatty acids
Multicellular, develop from embryos
Mostly symmetrical body organization
Heterotrophic by phagocytosis
i.e. humans, bees, shrimp, birds

26. Kingdom Animalia

27. Identifying Species
Dichotomous key is one way to identify an unknown species
Uses pairs of contrasting descriptive statements of physical characteristics to lead to the id of an organism or object
Uses the principle of forced choice, you must choose one description or the other
Does not evaluate evolutionary relationships

28. ID these: 1. a. wings covered by an exoskeleton ………go to step 2
b. wings not covered by an exoskeleton ……….go to step 3
2. a. body has a round shape ……….ladybug
b. body has an elongated shape ……….grasshopper
3. a. wings point out from the side of the body ……….dragonfly
b. wings point to the posterior of the body ……….housefly

29. Phylogenetics Phylogeny: evolutionary history of a species or taxon
Phylogenetics: analysis of evolutionary or ancestral relationships among taxa
Systematists: people who study phylogenetics
Use physical characterists, embryonic development, chromsomes and macromolecules (like nucleic acids)
Used a phylogenetic diagram or tree to represent relationships

30. Phylogenetics

31. Cladistics
System of phylogenetics that uses only shared and derived characteristics for grouping taxa
Shared characteristic: all members of a group have (hair in mammals)
Derived characteristic: evolved only w/in the group under consideration (feathers in birds)

32. Cladistics
Assumes organisms that share 1 or more derived characteristics come from a common ancestor
Clade: group of organsims that includes an ancestor plus all of its descendants
Use cladograms to represent relationships
Show probable evolutionary relationships
Two groups on diverging branches share 1 or more characteristic

33. Cladogram