Biodiversity and Classification

Biodiversity

  • Biodiversity is a large variety of living organisms on our planet and the interactions between them.
  • May 25th is the international day for biodiversity.

Importance of Biodiversity

  • Variety increases survival by enabling adaptation and evolution.
  • Species diversity: variety of species.
  • Genetic diversity: genetic variety within a species.
  • Ecosystem diversity: variety of ecosystems in an area.
  • Genetic diversity allows for a variety of species which in turn allows different species to occupy different ecosystems.

South Africa's Biodiversity

  • South Africa is the 3rd most biodiverse country with high species richness and endemism.
  • It's among the top 10 nations for plant species richness and has the 2nd highest plant endemism.
  • Three of the world's biodiversity hotspots are located in South Africa.

Species Numbers in South Africa

  • Includes percentages of world totals:
    • 23,420 plants (9%)
    • 6,859 marine vertebrates (8%)
    • 2,200 marine fish (15%)
    • 694 birds (7%)
    • 258 mammals (6%)
    • 363 reptiles (5%)

Key Concepts

  • Key species influence ecosystem health.
  • Indigenous species occur naturally in South Africa and elsewhere.
  • Endemic species are unique to a specific area.
  • Exotic/Alien species do not belong and are introduced.

Biodiversity and Ecosystem Stability

  • Greater biodiversity = greater ecosystem stability
  • Reduced dependence of one species on another for resources.
  • Important to maintain biodiversity to prevent ecosystem collapse.

Human Impact on Biodiversity

  • Human activities reduce biodiversity through:
    • Pollution
    • Habitat destruction
    • Overexploitation
    • Invasive species
    • Climate change
  • Impacts include:
    • Severe weather
    • Water issues
    • Pollination issues
    • Food/shelter insecurity

Maintaining Biodiversity

  • Reduce waste and increase recycling.
  • Breeding programs for endangered species.
  • Protect and regenerate habitats.
  • Replant trees.
  • Reduce deforestation and carbon emissions.

Taxonomy

  • Classification systems organize the diversity of life.
  • Taxa: groups into which organisms are classified.
  • Taxonomy: Science of classifying organisms assign each organism a universally accepted name.

History of Classification

  • Aristotle: first taxonomist, divided organisms into plants and animals.
  • Carl Linnaeus: developed the 2-kingdom classification system and a hierarchical system with 7 taxa.

Taxonomic Ranks

  • Domain (most inclusive)
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species (least inclusive)

Binomial Nomenclature

  • Each species has a 2-part scientific name (Genus species).
  • Italicized when typed, underlined when written.

5 Kingdom Classification System

  • Proposed by Robert Whitaker.
  • Criteria:
    • Body structure (unicellular/multicellular)
    • Cell structure (prokaryotes/eukaryotes)
    • Cell composition (cellulose/chitin/no cell wall)
    • Motility (mobile/immobile)
    • Nutrition (autotrophic/heterotrophic)
    • Reproduction (binary fission/asexual/sexual)

Terminology

  • Prokaryote: cells without a true nucleus or organelles.
  • Eukaryote: cells with a true nucleus and organelles.
  • Asexual reproduction: offspring are identical to the parent.
  • Sexual reproduction: involves male and female gametes.

Kingdoms Overview

  • Monera:
    • Unicellular, prokaryotic, asexual (binary fission), e.g., bacteria.
  • Protista:
    • Unicellular or multicellular, eukaryotic, asexual or sexual, e.g., protozoa, algae.
  • Fungi:
    • Unicellular (yeasts) or multicellular (mushrooms, molds), eukaryotic, heterotrophic.
  • Plantae:
    • Multicellular, eukaryotic, cellulose cell walls, autotrophic, sexual or asexual reproduction.
  • Animalia:
    • Multicellular, eukaryotic, no cell walls, heterotrophic, sexual reproduction.

Carl Woese

  • Discovered Archaebacteria and proposed classifying organisms by grouping kingdoms into domains.