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.