Biodiversity

• Biodiversity


  Three different measures:

  1. Species diversity - number of different species and individuals within each species in a community
  2. Genetic diversity - variety of genes amongst all the individuals in a population of just one species
  3. Ecosystem diversity - range of different habitats, can be on a small scale or the entire earth
• 1. level biology only focuses on species diversity, particularly species richness
• Species richness


  The number of different species in a particular area at a particular time
• Importance of biodiversity


  • Can be used to describe a range of habitats, from local to global

  Low biodiversity in some habitats (e.g. Arctic, desert) is not necessarily a concern as abiotic factors are harsh

  Decrease in previously high biodiversity is a concern, often caused by human activity
• Human activities that reduce biodiversity


  • Destruction of hedgerows

  Selective breeding

  Monoculture

  Overgrazing

  Filling in ponds/draining wetlands
• Compromises to conserve biodiversity while enabling farming


  Removing some but not all hedgerows

  Selective breeding in particular areas/for particular species

  Crop rotation or having different species in sections/rows of a field
• Index of diversity


  Measure that takes into account both the number of species and the number of individuals within each species

  Different from species richness which only considers the number of species
• Calculating Simpson's index of diversity


  N = total number of organisms of all species

  n = population size of one species

  Formula: Σ(n(n-1)) / N(N-1)
• Simpson's index of diversity typically falls between 3 and 6