Overview
This lecture explains biological classification (taxonomy), focusing on how organisms are grouped by shared characteristics, the classification hierarchy, and the use of scientific names.
Introduction to Taxonomy
- Taxonomy is the science of classifying living organisms by shared characteristics.
- Developed by Carolus Linnaeus in the 1700s, often called Linnaean classification.
- Knowing an organism's classification reveals much about its traits.
Hierarchy of Biological Classification
- The main levels of classification, from most to least inclusive: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
- Mnemonics help remember this order, e.g., "Do Kangaroos Prefer Cake Or Frosting, Generally Speaking?"
- A species is the most specific classification and includes organisms that can breed and produce fertile offspring.
Domains and Examples
- Three biological domains: Bacteria, Archaea, and Eukarya.
- Domain Eukarya includes animals, plants, fungi, and protists.
- Human classification: Domain Eukarya → Kingdom Animalia → Phylum Chordata → Class Mammalia → Order Primates → Family Hominidae → Genus Homo → Species sapiens.
Scientific Naming (Binomial Nomenclature)
- The scientific name uses the Genus and species, e.g., Homo sapiens.
- The Genus is capitalized, the species is lowercase; italicized if typed, underlined if handwritten.
- After first use, abbreviate the genus (H. sapiens).
- Dogs: Canis lupus (genus Canis, species lupus); domestic dogs are Canis lupus familiaris (a subspecies).
Importance of Scientific Names
- Scientific names often describe features in Latin or Greek, e.g., "leucocephalus" means "white head" in the bald eagle's name.
- Some names honor people, such as the fern genus named Gaga.
Classification Reveals Relationships
- Organisms in the same phylum may differ greatly in other levels; e.g., insects (six legs, antennae) vs. arachnids (eight legs, no antennae) are both arthropods but differ in class and order.
Key Terms & Definitions
- Taxonomy — the method of classifying organisms by shared traits.
- Hierarchy — ordered levels of classification from broad to specific.
- Binomial Nomenclature — two-part naming system using genus and species.
- Domain — most inclusive classification level.
- Species — group able to breed and produce fertile offspring.
Action Items / Next Steps
- Review and memorize the classification hierarchy and mnemonic.
- Understand how to write and interpret scientific names.
- Prepare for the next lecture on evolution and natural selection.