Classification of Living Things • Taxonomy: Branch of biology that names organisms according to their characteristics. • Putting things into orderly groups based on similar characteristics. • Why do scientists classify? • Biologists classify living organisms to answer questions such as: • How many known species are there? • What are the defining characteristics of each species? • What are the relationships between these species?
Aristotle (300 B.C.) • Aristotle • Greek philosopher and teacher more than 2000 years ago • The first person to group or classify organisms
Aristotle ANIMALS: PLANTS: Based on size of stem Based on where they lived
Limitations of Early Classification 1. Not all organisms fit into Aristotle’s 2 groups (plants or animals) Ex: Bacteria Fungi Images from: http://www.leighday.co.uk/upload/public/docImages/6/Listeria%20bacteria.jpg http://danny.oz.au/travel/iceland/p/3571-fungi.jpg
Limitations of Early Classification Ex: A jelly fish isn’t a fish, but a seahorse is! 2. Common names can be misleading Sea cucumber sounds like a plant but… it’s an animal! Image from: http://www.alaska.net/~scubaguy/images/seacucumber.jpg
Limitations of Early Classification 3. Common names vary from place to place Ex: puma, catamount, mountain lion, cougar are all names for same animal Image from: http://www4.d25.k12.id.us/ihil/images/Cougar.jpg
Limitations of Early Classification 4. Same organisms have different names in different countries. Chipmunk Streifenhornchen (German) Tamia (Italian) Ardilla listada (Spanish) Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm
Limitations of Early Classification • Early Solution: • Description of Organism Using Latin Names RED OAK Quercus foliis obtuse-sinuatis setaceo-mucronatis “oak with leaves with deep blunt lobes bearing hairlike bristles”
Limitations of Early Classification • Problem with Latin Name descriptions? • Names too long and difficult to remember • Names don’t illustrate evolutionary relationships
Carolus Linneaus Devised a new classification system based on morphology (Organism’s form and structure) (1707-1778) “Father” of taxonomy and binomial nomenclature
Carolus Linnaeus • Linnaeus’s Classification System • Organisms grouped in a hierarchy of seven different levels • Each organism has a two part scientific name • Binomial Nomenclature
Kingdom • Phylum • Class • Order • Family • Genus • Species Kids Prefer Cheese Over Fried Green Spinach
Kingdom • Phylum • Class • Order • Family • Genus Species Animalia Chordata Mammalia Carnivora Felidae Panthera leo http://www.vetmed.wisc.edu/dms/fapm/personnel/tom_b/2004-lion.jpg
Binomial Nomenclature • Binomial Nomenclature: Two name naming system • Italicized or Underlined • 1st Name = Genus • Capitalized • 2nd Name = Species Identifier • Lower case
Binomial Nomenclature Vampire batDesmodus rotundus Image from: http://18.104.22.168/i/Vampire%20Bat.jpg Eastern chipmunk Tamiasstriatus Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm
Binomial Nomenclature Humans Homo sapiens Homosapiens Image from: http://www.earlylearning.ubc.ca/images/photo_baby.jpg
Modern Taxonomy Modern taxonomy involves the use of Linnaeus’s naming/classification system, but with additional kingdoms.
Modern Taxonomy • Organizes living things in the context of evolution
Modern Taxonomy • Scientists use a variety of information in order to classify organisms: • Fossil Record • Morphology • Embryology • Chromosomes • Macromolecules (DNA and Proteins)
1. FOSSIL RECORD We can trace some changes over time through the fossil record. Evolutionary history = PHYLOGENY
2. MORPHOLOGY Shape and Function Image from: http://www.angelfire.com/ab7/evolution12/evolutionclues.html
Morphology • Homologous Characteristics: • Same embryological origin (may have similar structure and function) • Example: Bat Wing and Human Arm Homologous characteristics suggest a recent common ancestor
Morphology Bat wing and human arm develop from same embryonic structures HOMOLOGOUS STRUCTURES
Morphology • Analogous Characteristics: • May have similar structure and function, but different embryological origin • Example: Bird Wing and Butterfly Wing Analogous characteristics evolved separately. Organisms not necessarily closely related.
ANALOGOUSSTRUCTURES Bird wing and butterfly wing have evolved with similar function BUT different structure inside. http://uk.dk.com/static/cs/uk/11/clipart/bird/image_bird003.html Insects and birds NOT closely related! http://www.naturenorth.com/butterfly/images/05a%20tiger%20wing.jpg
I don’t get it! • Analogous characters the same function but different underlying construction. • Homologous characters different functions, but show an anatomical similarity inherited from a common ancestor. **Important for cladograms!**
3. Embryology Animals whose embryos develop in a similar pattern may be related Image from: http://calspace.ucsd.edu/virtualmuseum/litu/03_3.shtml
Even differences show relatedness amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid http://www.southtexascollege.edu/nilsson/4_gb_lecturenotes_f/4_gb_24_cla_ani_ve_spr2003.html
4. Chromosomes Similar karyotypes suggest closer relationships. Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
Human- 46 chromosomes Chimpanzee- 48 chromosomes Even differences show relatedness Chimpanzees have 2 smaller chromosome pairs we don’t have Humans have 1 larger chromosome pair (#2) they don’t have. Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
5. Macromolecules Comparison of macromolecules such as Proteins and DNA Organisms with similar sequences are (thought to be) more closely related.
Evolutionary Relationships • Determined through the use of: • Morphology • Fossil Record • Embryology • Chromosomes • Macromolecules Evolutionary relationships can be illustrated on a phylogenetic tree
Cladistics Phylogeny: Evolutionary History Shows evolutionary relationships based on “shared derived characteristics” Cladistic relationships illustrated through the use of a Cladogram
Cladogram • The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor.
Domains Do Kids Prefer Cheese Over Fried Green Spinach? • Domains are taxonomic groups that are even bigger than kingdoms. Each of the six kingdoms belongs to a single domain. • Three Domains: • 1. Archaea • 2. Bacteria • 3. Eukarya
Domain Bacteria • Eubacteria are prokaryotes whose cell walls contain peptidoglycan. • “True bacteria”
Domain Archaea • Archaea are thought to be more ancient than bacteria and yet more closely related to our eukaryote ancestors. • Cell walls without • peptidoglycan • They are called extremophiles because they can live in extreme environments.
Domain Eukarya • All eukaryotes are classified in Domain Eukarya. • Domain Eukarya contains Kingdom Protista, Kingdom Fungi, Kingdom Plantae, and Kingdom Animalia.
Kingdom Archaebacteria Some archaebacteria are heterotrophs, but some are autotrophs. Most archaebacteria are unable to move, but a few can move. Archaebacteria are the old known life forms. Why are archaebacteria not classified with “modern bacteria”? Archaebacteria and eubacteria are chemically different!
Kingdom Archaebacteria Cool archaebacteria info: Three divisions of archaebacteria:Methanogens: methane producing organisms Thermophiles: These can live in extremely hot, acidic environments like sulfur springs. Halophiles: Can only live in bodies of concentrated salt water, like the Dead Sea.
Kingdom Eubacteria Traditional prokaryotic bacteria Unicellular. Some are autotrophic, some are heterotrophic. Found in soil, water, human body, etc. Esterichia coli (E. coli) is found in large numbers in human intestines, where it produces vitamin K.
Kingdom Eubacteria Unlike archaebacteria, eubacteria require oxygen. Some bacteria contain cilia or flagella which allows them to move.
Kingdom Protista • Eukaryotic organisms. • This is why they are not considered bacteria! • Most protists are single-celled but some are simple, multicellular organisms • “Junk Drawer Kingdom” or “Odds and Ends Kingdom” • Some protists are autotrophic, some protists are heterotrophic. • Animal-like protists, plant-like protists
Kingdom Protista Most protists are able to move, but some cannot
Kingdom Fungi Molds and mushrooms are examples of fungi. Fungal cell walls contain chitin. (cell walls of plants contain cellulose). The study of fungi is known as mycology. Fungi are more closely related to animals than to plants! Usually, the only fungi that we see are reproductive structures. Tasty!!