biodiversity, species and taxonomy

• Organisms belong to the same species if they interbreed in their natural habitat to produce fertile offspring
• Successful interbreeding or mating is preceded by some form of courtship behaviour
• Courtship in animals is a behavior that eventually results in mating and reproduction
• Courtship can be a simple process involving a small number of visual, chemical, or auditory stimuli
• Courtship can also be a complex sequence of acts by two or more individuals, using several modes of communication
• Many birds of paradise have intricate and impressive courtship rituals
• Courtship plays a major role in species recognition
• In Drosophila fruit flies, different species have distinct courtship rituals aiding in species recognition
• The male fruit fly's courtship dance sequence is controlled by several genes and is specific to each species
• A female fruit fly will not respond to or mate with a male that displays an incorrect courtship dance
• Females also have specific actions to communicate disinterest to the male
• Organisms belong to the same species if they interbreed to produce fertile offspring
• Taxonomy is the practice of biological classification
• The phylogenetic classification system enables arranging species into groups based on their evolutionary origins and relationships
• Each group in taxonomy is called a taxon (plural taxa)
• Grouping organisms into taxa makes them easier to understand and remember
• There are several ranks or levels within the hierarchical classification system used in biology
• The highest rank in the classification system is the domain
• Cell type plays a major role in classifying organisms into the three domains
• Prokaryotic cells lack a nucleus, while eukaryotic cells have compartmentalised structures with genetic material segregated in a nucleus
• Scientists realized that using cell type to classify organisms is insufficient, leading to the division of prokaryotes into two separate groups (domains)
• The three domains are:

  • Archaea (prokaryotes)
  • Bacteria (prokaryotes)
  • Eukarya (eukaryotes)
• Archaea domain:

  • Organisms are sometimes referred to as extremophile prokaryotes
  • Archaea have no nucleus and were initially classified as bacteria until unique properties were discovered
• Unique properties of archaea that separate them from bacteria include:

  • Unique lipids in cell membranes
  • No peptidoglycan in cell walls
  • Ribosomal structure more similar to eukaryotes
• Bacteria:

  • Organisms with prokaryotic cells lacking a nucleus
  • Vary in size from smallest bigger than largest known viruses to largest smaller than smallest known single-celled eukaryotes
  • Divide by binary fission
• Eukarya:

  • Organisms with eukaryotic cells containing nuclei and membrane-bound organelles
  • Vary in size from single-celled to large multicellular organisms
  • Divide by mitosis
  • Can reproduce sexually or asexually
• Biodiversity is the variation within and between all forms of life
• Biodiversity is crucial for the resilience of ecosystems, allowing them to resist changes in the environment
• Ecosystem or habitat diversity refers to the range of different ecosystems or habitats within a particular area or region
• Areas with a large number of different habitats have high biodiversity, while those with only one or two habitats have low biodiversity
• Species diversity measures the mix of different species within a particular area or region
• Species richness is the number of species within a community
• Species diversity also considers the evenness of abundance across the different species present in a community
• Ecosystems with high species diversity are more stable and resilient to environmental changes compared to those with lower species diversity