Lecture Notes: Diversity and Classification of Life

Introduction: What is Diversity?

• Diversity is crucial to study because:
  • Much of earth's diversity could be lost in the future.
  • Knowledge of organisms helps in identifying disease-causing agents.
  • Many drugs are derived from natural sources.
• Biodiversity Definition: Number of different species of organisms in a specific environment.
  • Can be defined through ecosystems, species, or genetics.
  • Species defined by genetic integrity; reproductive community in a specific niche.

Taxonomy: Classification of Living Things

• Taxonomy: Classification or cataloguing of living things.
• Taxonomists: Biologists who classify organisms into a hierarchical system.

Living vs Non-Living

• Living Characteristics:
  • Made of cells, responds to environment, grows, obtains/uses energy, reproduces.
• Non-Living Characteristics:
  • Does not exhibit all characteristics of life.
• Examples:
  • Living: Bacteria, Plants, Animals, Fungi.
  • Non-Living: Viruses, Prions.

Binomial System of Classification

• Carolus Linnaeus: Father of Taxonomy, described 7300 species.
• Good Classification System:
  • Orderly information, agreed terms, inclusion of new organisms.
• Taxonomic Keys: Dichotomous tool to name/classify organisms.
• Taxonomic Groups: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Binomial Nomenclature: Two-part Latin name for species (Genus capitalized, species lowercase).

The Five Kingdoms of Life

• Proposed by Robert Whittaker (1959):
  • Monera: Prokaryotic, unicellular organisms.
  • Protista: Eukaryotic, single-celled organisms.
  • Fungi: Multicellular, heterotrophs, decomposers.
  • Plantae: Multicellular autotrophs, photosynthesis.
  • Animalia: Multicellular heterotrophs, motility.

Domains or Superkingdoms (Carl Woese, 1990)

• Archaea: Prokaryotic, extreme environments.
• Bacteria: Prokaryotic, peptidoglycan cell walls.
• Eukarya: Eukaryotes with membrane-bound organelles.

Overview of Kingdom Characteristics

• Monera:
  • Prokaryotic, unicellular, autotrophic/heterotrophic.
  • Examples: Archaebacteria, Eubacteria (Cocci, Bacilli, Spirilli).
• Protista:
  • Eukaryotic, unicellular, autotrophs/heterotrophs.
  • Examples: Algae (photosynthesis), Protozoa (feeding on organic matter).
• Fungi:
  • Eukaryotic, multicellular, absorb nutrients.
  • Examples: Mushrooms, molds.
• Plantae:
  • Eukaryotic, multicellular, autotrophs (photosynthesis).
  • Examples: Mosses, ferns, angiosperms.
• Animalia:
  • Eukaryotic, multicellular, heterotrophs, motile.
  • Examples: Vertebrates, invertebrates.

Ecological Importance of Kingdoms

• Monera: Decomposition, photosynthesis, nitrogen fixation.
• Protista: Nutrient producers, symbiotic relationships, photosynthesis.
• Fungi: Decomposition, nutrient cycling, symbiosis.
• Plantae: Oxygen production, food source, ecosystem balance.
• Animalia: Seed dispersal, pollination, nutrient recycling.