Introduction to Biological Diversity: Taxonomy

Context and Concepts

• Human Grouping Tendency: Humans have an inherent tendency to group things together.
• Taxonomy: The discipline of naming organisms and placing them into classification categories.
• Nomenclature: A system of agreed-upon rules for naming things.

Challenges in Common Language and Intuition

• Language and intuition can lead to inconsistencies across cultures.
• Examples:
  • Different names for the same organism (e.g., Crow = Krhe).
  • Incorrect biological relationships (e.g., Magpie classifications).
  • Non-existing relationships (e.g., fish names in fisheries).
• Example from Ilhabela, Brazil: Different fish names and classifications among artisanal fishermen.

Folk Taxonomy

• All languages categorize organisms through informal taxonomic schemes.
• These are traditional and evolve with language but may not capture true biological relationships.
• Example: Classification differences among the same teleost species, Amphilophus labiatus.

The Linnaean System of Nomenclature

• Developed by Carl Linnaeus (1707-1778).
• Pre-evolutionary Context: Based on creationistic views.
• Features:
  • Hierarchical classification based on similarity.
  • Use of binomial nomenclature for unique species identification.

Example of Hierarchical Ranks

• Ranks move from specific to broader categories:
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Example: Chinese alligator (Alligator sinensis)
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Reptilia
  • Order: Crocodylia
  • Family: Alligatoridae
  • Genus: Alligator
  • Species: sinensis

Binomial Nomenclature

• Two-Part Naming System
  • First part: Genus (capitalized).
  • Second part: Species (lower-case).
  • Format: Italicized binomial name, authority, and year.
• Example: Iris germanica (Linnaeus, 1753)

Limitations of the Linnaean Classification

• High-level ranks may not be comparable across groups.
• Informative features may vary among groups (e.g., presence of a backbone).
• Does not represent evolutionary relationships across taxa (e.g., dessert plants).

Summary

Linnaean taxonomy provides a foundational structure for classifying organisms but has limitations in capturing evolutionary relationships and comparable features across diverse groups. It highlights the necessity for a more inclusive system that considers genealogy and evolutionary biology.