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Classification of Living Things. Classification of Living Things. Taxonomy : science of classification Branch of biology that names organisms according to their characteristics, and places them into orderly groups based on similar characteristics. Why ?
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Classification of Living Things • Taxonomy: science of classification • Branch of biology that names organisms according to their characteristics, and places theminto orderly groups based on similar characteristics. • Why ? • 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 (350 B.C.) • Aristotle • Greek philosopher and teacher more than 2000 years ago • The first person to devise a classification system-according to natural environment
Aristotle ANIMALS: PLANTS: Based on size of stem Based on where they lived
John Ray • 17th Century • Classified according to characteristics • Why are there problems with this???
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) • Formed a species • Similar species group together to form a genus (1707-1778) “Father” of taxonomy and binomial nomenclature
Use of genus and species names to form scientific name • This system is called binomial nomenclature • Binomial means two parts • Nomenclature means system of naming • Latin is used-dead language
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://212.84.179.117/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
Robert Whittaker-1969 • 5 kingdom system of naming • Animalia, Plantae, Protista, Monera, Fungi • Levels of classification from broadest to narrowest • KPCOFGS
Kingdom • Phylum • Class • Order • Family • Genus • Species Kings Play Cards On Fat Green Stools
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
Modern Taxonomy Modern taxonomy involves early naming/classification system, but with additional kingdom. Domain is the most general grouping
Modern Taxonomy • Organizes living things in the context of evolution
Modern Taxonomy • Scientists use a variety of information in order to classify organisms: • Chromosome Structure • Reproductive Potential • Biochemical Makeup/Protein Comparison • Morphology- Homologous Structures
1. Chromosomes Similar karyotypes suggest closer relationships. Indicates similar DNA/RNA structure by comparing base sequences 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.
2. Reproductive potential • If two organisms can interbreed AND produce fertile offspring they are considered of the same species
3. Biochemical makeup Comparison of macromolecules such as Proteins Similar amino acid sequences in proteins indicate similar organisms
4. MORPHOLOGY Shape and Function Image from: http://www.angelfire.com/ab7/evolution12/evolutionclues.html
Morphology • Homologous Structures: • Embryological source of similar structures indicate a possible common ancestor • Example: Bat Wing and Human Arm • P. 262
Morphology Bat wing and human arm develop from same embryonic structures HOMOLOGOUS STRUCTURES
Morphology • Analogous Characteristics: • May have similar 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?!Think in terms of structure. • Analogous characters the same function but different underlying structure. • Homologous characters different functions, but similar structure inherited from a common ancestor. **Important for cladograms!**
Cladistics Phylogeny: Evolutionary History Reflect an organism’s 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.
Dichotomous Key A dichotomous key is used to classify an organism by physical characteristics. Made of couplets of opposing meaning.
Domain Bacteria Archaea Eukarya