BIO153 Lecture 3 notes

Introduction to Naming Organisms

• Human beings categorize and name things in various domains (e.g., clothing, stories).
• Consistency in naming helps avoid confusion.

The Importance of Naming in Biology

• Organisms have common names that may be useful but lack specificity.
  • Examples:
  • Broad names like bear and fish.
  • Specific names like grizzly bear and sockeye salmon.
• Common names can lead to confusion:
  • Example: The term cougar has multiple names (panther, mountain lion, catamount, puma, etc.).
• Some common names do not accurately reflect biological classifications:
  • Jellyfish, catfish, crayfish, and silverfish — only one is a true fish.

Variability in Common Names

• In Japan, fish may be given different names based on age and size:
  • Young fish have different categories based on their size, which leads to confusion in scientific contexts.
  • Example categories for Japanese amberjack:
  • Mojaco (~7 cm)
  • Wakashi (~15 cm)
  • Inada (~40 cm)
  • Warasa (~60 cm)
  • Buri (over 90 cm)

Systematics

• Systematics study focuses on classifying organisms and determining their evolutionary relationships.
• Interconnections between organisms and names can lead to confusion (e.g., the relationship of cats and catfish).

Binomial Nomenclature

• Developed by Carolus Linnaeus (1707-1778).
• First to consistently use a two-part naming scheme (binomial nomenclature).
  • Established in his work Species Plantarum (1753).
• The scientific name consists of:
  • Genus (group of related organisms)
  • Species (unique identifier for an organism)
• Example:
  • Puma: Puma concolor
  • Seriola: Seriola quinqueradiata

Rules for Binomial Nomenclature

1. Scientific names are italicized (underlined if handwritten).
2. Genus name is capitalized; species name is lowercase.
3. Both names are used to refer to species (e.g., Puma concolor).
4. Genus name can be abbreviated after first use (e.g., P. concolor).

Features of Binomial Nomenclature

• Names must be consistent, unique, and universal.
• The system is hierarchical and expandable.
• Organisms are classified into larger categories.
• Example classification for the North American beaver:
  • Domain: Eukarya
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Rodentia
  • Family: Castoridae
  • Genus: Castor
  • Species: Castor canadensis

Taxonomy and Hierarchical System

• Taxon (plural, taxa) refers to each layer of classification.
• All taxa names, except for Genus/species, are non-italicized with the first letter uppercase.
• Taxonomy structure is expandable (e.g., sub-order under Order).

International Naming Organizations

• Naming governed by international codes:
  • International Code of Zoological Nomenclature (ICZN) for animals.
  • International Code of Nomenclature for algae, fungi, and plants (ICN).
  • International Code of Nomenclature of Prokaryotes (ICNP) for bacteria and archaea.
  • International Committee on Taxonomy of Viruses (ICTV) for viruses.

Understanding Systematics

• Classification can be arbitrary, based on human decisions.
• Example: Spruces, pines, and firs are grouped differently but may be closely related.
  • Example organisms:
  • Scots Pine: Pinus sylvestris
  • Norway Spruce: Picea abies
  • Silver Fir: Abies alba

Diversity in Taxonomic Classification

• Taxonomic grouping may not reflect true biological diversity.
• For example, a genus may contain only one species (Cheetah: Acinonyx jubatus) while another genus (Felis) contains multiple species (e.g., Domestic Cat, Wildcat).
• The grouping may imply equivalent diversity which is not the case:
  • Cheetah belongs to family Felidae, while other families (e.g., Canidae, Procyonidae) contain entirely different animal types.

Conclusion

• The classification and naming of organisms is complex and influenced by both biological relationships and human choices.
• Understanding binomial nomenclature is essential for clarity in biological sciences.