Biodiversity and Classification Notes

Biodiversity Overview

• Estimates suggest 8-10 million different species on Earth, with only 20% identified.
• Biodiversity: Variety within and among living species.

Biological Classification

• Systematists: Scientists who classify organisms into groups.
  • Involves collections of animals, plants, fungi, and microbes in natural history museums, herbaria, type-collection centers, etc.

Major Eras and Periods in Geological History

• Precambrian: Formation of Earth, first simple organisms.
• Paleozoic Era: Major developments include:
  • Cambrian (495 million years ago): Rapid emergence of diverse life forms.
  • Ordovician (439 million years ago): Life begins to dominate in oceans.
  • Silurian (408 million years ago): First land colonization by simple plants.
  • Devonian (354 million years ago): Age of fishes.
  • Carboniferous (290 million years ago): Dominance of seedless plants.
  • Permian (251 million years ago): Mass extinction ends the era.
• Mesozoic Era: Age of dinosaurs.
  • Triassic (206 million years ago), Jurassic (144 million years ago), and Cretaceous (65 million years ago): Evolution and diversification of reptiles and the emergence of flowering plants.
• Cenozoic Era: Post-dinosaur extinction biodiversity explosion, including mammals and birds.

Biological Taxonomy

• The biological classification system follows a hierarchy:
  • Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
  • E.g., Human classification is:
  • Domain: Eukarya
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Primates
  • Family: Hominidae
  • Genus: Homo
  • Species: Homo sapiens

The Three Domains of Life

• Domain Bacteria: Prokaryotic, unicellular organisms.
• Domain Archaea: Prokaryotes typically found in extreme environments.
• Domain Eukarya: Eukaryotic organisms (includes Protists, Plants, Animals, and Fungi).

Evolutionary Relationships

• DNA Comparisons: Method to determine evolutionary relationships.
  • Closer related organisms have similar DNA sequences.

Microbial Life

• Microbes play crucial roles:
  • Produce over half of Earth's atmospheric oxygen.
  • Key decomposers in ecosystems.
  • Dominant life forms by biomass exceeding that of larger organisms.