Intro To Biodiversity & Classification Of Organisms

Biological Species Concept

  • Definition of Species: A population of organisms whose members can breed freely in nature to produce fertile offspring.
  • Barriers to Interbreeding: Ecological, behavioral, and physical differences usually prevent different species from interbreeding.

Biodiversity

  • Definition: The number and variety of species and ecosystems on Earth.
  • Importance: Higher biodiversity contributes to the ecosystem's resilience against environmental changes.
  • Keystone Species: Species that have a disproportionately large effect on their ecosystem; their absence can lead to significant changes.
    • Example: Pesticides reducing pollinator populations leading to food scarcity.

Genetic Diversity

  • Definition: The genetic variability among organisms, particularly within the same species.
  • Formation of Genetic Diversity: Result of sexual reproduction, producing unique offspring with inherited genetic information from both parents.
  • Significance: Enables populations to adapt to environmental changes.

Species Diversity

  • Definition: Measures both the quantity of each species and the variety of different species present in an ecosystem.
  • Contributions: Each species plays a role in the ecosystem's ability to withstand environmental changes.

Ecosystem Diversity

  • Definition: The variety of habitats, organisms, and their interactions within a specific environment.
  • Structural Diversity: Refers to varied habitat structures that support more microhabitats and a wide range of species interactions.
    • Examples: Food sources, protection, reproduction, and other ecological needs.

Societal Impacts of Biodiversity Loss

  • Human Impacts: Loss of biodiversity can lead to:
    • Threatened food supply.
    • Loss of natural medicine sources.
    • Economic impacts on sectors like tourism and forestry.
    • Disruptions in biogeochemical cycles.

Case Study: Honeybees

  • Role: Crucial pollinators in ecosystems.
  • Current Threats: Declining global populations due to factors like pesticide use and viral infections from parasites.

Classification of Organisms

  • Classification Systems: Provide frameworks for organizing living organisms based on characteristics and relationships.
  • Common Categories: Can classify organisms using various systems; examples provided include plants, animals, and microorganisms.

Biological Classification

  • Definition: Systematic grouping of organisms based on evolutionary and physical characteristics.
  • Observable Characteristics: Morphology, behavior, and geographic location.

Taxonomy

  • Definition: The science of naming, identifying, and classifying all organisms.
    • Example of Taxonomic Hierarchy:
    • Kingdom: Animalia
    • Phylum: Chordata
    • Class: Mammalia
    • Order: Carnivora
    • Family: Ursidae
    • Genus: Ursus
    • Species: Ursus arctos

Binomial Nomenclature

  • Overview: Developed by Carl Linnaeus to give each organism a unique two-part name.
  • Naming Convention: Each species has a genus name followed by a specific name (e.g., Escherichia coli). The genus is capitalized, and the entire name is italicized.

Taxons

  • Taxonomic Levels: Organisms are categorized into levels based on shared features. Common ranks include:
    • Species, Genus, Family, Order, Class, Phylum, Kingdom.

Modern Classification

  • Evolution of Classification: Original classification based on morphology has evolved to include evolutionary relationships due to insights from Darwin's theory of evolution (1859).
  • Molecular Approaches: Advances in technology have allowed for the inclusion of genetic and molecular data in determining evolutionary relationships.

Phylogeny

  • Definition: The study of the evolutionary relatedness between species.
  • Phylogenetic Trees: Diagrams that illustrate hypotheses of evolutionary relationships among species.

Domains of Life

  • Introduction of Domains: Advances in phylogenetic studies have led to a classification system that includes three domains:
    • Bacteria: Microscopic prokaryotes without membrane-bound organelles.
    • Archaea: Microscopically similar to bacteria but with distinct biochemistry and genetics.
    • Eukarya: Multicellular and unicellular organisms with membrane-bound organelles (includes plants, animals, fungi).

Differences between Prokaryotes and Eukaryotes

  • Genetic Material: Prokaryotes have free-floating, non-coated DNA; eukaryotes have DNA within nucleus.
  • Cell Division: Prokaryotes utilize fission; eukaryotes undergo mitosis and meiosis.
  • Respiration: Prokaryotes may not require oxygen, while eukaryotes almost always do.
  • Size: Generally, prokaryotes are microscopic, whereas eukaryotes can be macroscopic.