Taxonomy Notes

Introduction to Taxonomy

  • Taxonomy is the science of classifying and naming organisms.
  • Systematics studies biological diversity and evolutionary relationships.
  • Sometimes, taxonomy and systematics are used interchangeably.

Biological Classification

  • Classification arranges organisms into a hierarchical system.
  • Classification approaches:
    • Artificial
    • Natural
    • Phylogenetic

History of Biological Classification

  • Aristotle classified living things by type and introduced binomial definition.
  • He grouped organisms by habitat (land, water, air) and plants into shrubs, trees, and herbs.

Carolus Linnaeus

  • Linnaeus developed a hierarchical ranking system and binomial nomenclature.
  • Binomial nomenclature: assigns a unique two-part name (genus and species) to each species.

Nomenclature

  • Nomenclature is the process of naming species.
  • Types of naming approaches:
    • Common names
    • Binomial nomenclature
    • Trinomial nomenclature
    • Polynomial nomenclature
  • Binomial nomenclature is most widely used.

Rules of Binomial Nomenclature

  • Governed by international codes:
    • International Code of Zoological Nomenclature (ICZN) for animals
    • International Code of Botanical Nomenclature (ICBN) for plants, fungi, and algae
    • International Code of Nomenclature for Cultivated Plants (ICNCP) for cultivated plants
    • International Code of Nomenclature of Prokaryotes (ICNP) for bacteria and archaea
    • International Code of Viral Nomenclature (ICVN) for viruses

Taxonomic Hierarchy

  • Organizes organisms into groups based on similarities.
  • Levels (from general to specific):
    • Domain
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family
    • Genus
    • Species

Phylogeny

  • Phylogeny describes the evolutionary history of relationships among organisms.
  • Represented by a phylogenetic tree.
  • Each node represents a divergence point.
  • The root represents the common ancestor.

Constructing Phylogenetic Trees

  • Traits used: morphological, fossil, developmental, molecular, behavioral.
  • Cladistic approach: reconstructs trees by considering evolutionary pathways.
  • Cladistics compares shared traits.
  • Mathematical models describe DNA changes.