Lecture on Taxonomy

Overview

• Discussion on taxonomy and organization of living organisms.
• Taxonomy is likened to a "file cabinet" of living organisms.

Taxonomic Levels

• Domains: Broadest taxonomic level; origin of all living organisms.
  • Bacteria:
    • Single-celled, prokaryotes, unicellular, no nucleus, cell wall.
  • Archaea:
    • Single-celled, prokaryotes, different cell wall materials, extremophiles (live in harsh environments).
  • Eukaryotes:
    • Single or multicellular, have a nucleus, some have cell walls (e.g., plants, humans).

Identifying Eukaryotes

• Examples: House sparrow, tree, amoeba (all are eukaryotes).
• Bacteria (e.g., E. coli) is not a eukaryote.

Taxonomic Rankings

• Order from broadest to most specific:
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Example: Domestic Dog

• Scientific Name: Canis lupus
  • Also the name for gray wolves (domestic dogs are artificially selected from gray wolves).
• Genus: Canis (includes coyotes and domestic dogs).
• Family: Canidae (includes all canines like coyotes, gray wolves, foxes).
• Order: Carnivora (all mammalian carnivores, e.g., tigers, lions, canines).
• Class: Mammalia (e.g., rabbits, deer, whales).
• Phylum: Chordata (anything with a spinal cord, e.g., komodo dragons, snakes).
• Kingdom: Animalia (all animals, excluding those without a spinal cord, e.g., spiders).

Mnemonics for Taxonomic Levels

• "Dear King Philip Came Over For Good Soup"
• "Do Kangaroos Prefer Cake Or Frosting Generally Speaking"

Phylogeny

• A phylogeny is a tree showing relationships of living things based on taxonomy.
• Relation examples:
  • Domestic dogs (Canis lupus) closely related to coyotes.
  • Calculate branch lengths to determine relatedness.
  • Example placements: Squirrels (non-carnivores, mammals); Mountain lions (carnivores, mammals).

Scientific Names

• Consist of two words: Genus and specific epithet.
• Genus: Capitalized
• Specific epithet: Not capitalized
• Written in italics.
• Genus can stand alone but not the specific epithet.
• Example: Tyrannosaurus rex
  • Refer to whole genus or specific species.

Practice

• Find and write scientific names.
• Identify genus and specific epithet.
• Be familiar with writing and understanding scientific names.

Conclusion

• Importance of using scientific names.
• Encouragement to ask questions if needed.