4.3 Biodiversity

• species diversity


  the number of different species and individuals within each species in a community
• genetic diversity


  the variety of genes amongst all the individuals in a population of one species
• habitat diversity

  the range of different habitats
• species richness

  the number of different species in a particular area at the particular time
• what can you use to catch small insects?

  pooter - sucking on a mouthpiece
• sweep nets 


  catch insects in areas of long grass
• pitfall traps


  catch small, crawling invertebrates.

  • hole dug deep into ground
• point quadrat 


  at set intervals along the bar, pins can be pushed through the bar to reach the ground
• 3 levels of biodiversity

  1. habitat: number of diff habitats
  2. species: richness and evenness
  3. genetic: variety of genes
• genetic biodiversity


  the variation caused by genes, between individuals belonging in the same species. It ensures that individuals are not all identical
• genetic bottleneck


  when only a small number of a population have survived an event.

  • the gene pool is decreased and only the alleles in the remaining population can be passed on to future offspring
• founder effect


  when a small number of individuals from a population decide to colonise a new isolated area
• polymorphic gene


  gene that has more than one allele
• genetic diversity calculation


  proportion of polymorphic gene loci = number of polymorphic gene loci / total number of loci

  • the higher the proportion of polymorphic gene loci, the larger the genetic diversity within the population
• simpson's index of diversity

  D = N(N-1) / sum of n(n-1)
• to ensure sample is representative of population:

  • take a large sample
  • randomly sample to avoid bias
• pitfall trap

  • dig hole and place container in soil
  • make top of container level with soil level
  • cover to protect from, rain / scavengers
  • leave overnight
  • identify / count, (named) invertebrates
  • sample both areas, randomly / at 5(+) sites
• kick sampling


  investigator gently kicks river bed to disturb earth and the organisms within it. A second investigator stands behind them with a net to capture any organisms that are released.
• in situ conservation (within natural habitat)


  • genetic diversity maintained as individuals not bred captively
  • all organisms interdependent so preventing extinction of one species will positively impact other species dependent on it.
• ex situ conservation (not within natural habitat)

  • botanical gardens, seed banks, captive breeding
  • seed banks store seeds as a back up for plants that may go extinct
• CITES


  Convention on International Trade in Endangered Species

  • regulates trade of international animals, plants and their products
• CBD


  The Rio Convention on Biological Diversity

  • began in 1992 when 172 nations met in Rio
  • countries must come up with strategies for sustainable development
  • stabilise greenhouse gas emissions and concentrations within the atmosphere
  • to prevent the destruction of fertile land into desert and reduce effects of drought
• CSS


  The Countryside Stewardship Scheme