4.2.1 - Biodiversity

• Biodiversity is the variety of living organisms.
• Species diversity is the number of species in a community
• Habitat diversity is the range of different habitats
• Genetic diversity is the variety of alleles within a species
• Species richness is the number of species in an area
• Species evenness is whether the species have similar numbers
• Random sampling is no particular system but aims to be representative
• Opportunistic sampling is those that are encountered first are chosen
• Stratified sampling is when the population is divided into smaller groups based on characteristics then sampled
• Systematic sampling follows a particular pattern
• Sampling is important as we cannot study the whole population as it is impractical. So using a representative sample instead allows us to investigate the population easily.
• Simpsons index of diversity is used as a measurement of the total number of organisms compared to the total number of organisms of each species.
• A high index of diversity means several different species are equally abundant

  whereas a low index means one or two species dominate over others
• To assess genetic diversity you can calculate the

  proportion of polymorphic gene loci = ( number of polymorphic gene loci / total number of loci ) x 100
• Factors that affect biodiversity are

  • Population growth
  • deforestation for agriculture
  • climate change affecting habitats
• Conservation is the protection and management of species and habitats in order to maintain biodiversity. Can be in-situ or ex-situ.
• In-situ conservation is within an organisms habitat
• Ex-situ conservation is outside of an organisms habitat
• Examples of in-situ conservation include:

  • marine conservation zones
  • wildlife reserves
• Examples of ex-situ conservation include

  • Seed banks
  • botanic gardens
  • zoos
• There are some agreements made with the aim of protecting species and habitats including:

  convention on international trade in endangered species (CITES)

  Rio convention on biological diversity (CBD)

  countryside stewardship scheme (CSS)
• There are four main reasons to maintain biodiversity:

  1. ecological: protecting species and resources
  2. Genetic resource: potential medicines
  3. economic: reduce effects of soil depletion
  4. aesthetic: protecting landscapes
• species: being able to breed to produce fertile offspring
• The different levels of biodiversity are genetic diversity, species diversity, and ecosystem diversity.
• species richness is the number of species within an area
• A habitat is the area where individuals in a species live
• It is important to keep the gene pool large so that we are able to withstand disease
• Genetic biodiversity is different breeds within a species
• Biodiversity is:

  variety of life

  variety of ecosystems

  variety of genes

  number of species
• species evenness is the number of individuals within each species
• You can measure species richness by counting the number of species within an area
• In simpsons index of diversity

  n = the number of individuals of a particular species

  N = total number of all individuals of all species
• High Sampson’s index (closer to 1)

  high biodiversity, high species richness, high species evenness

  ecosystem is stable and likely to withstand a change
• Low simpsons index (closer to 0)

  Dominated by one species

  change in one species is likely to affect the whole habitat

  ecosystem is unstable and unlikely to withstand a change
• Sampling must be random to avoid bias

  to get random samples you can take samples at Regular intervals along a transect

  generate random numbers as coordinates
• the number of samples used must be representative of the area

  you need many samples to calculate the mean but avoid recounting the same plant

  you should sample at different times of the year, month, day, weather conditions
• To sample we use quadrats and calculate the % cover or the number of individuals of each species.
• To use a belt transect:

  use a quadrat every … m

  count the number of organisms of each species and use an identification key

  calculate a mean and repeat at different times of the year
• to use a line transect count the organisms touching the line in a given area.
• To sample fields, use two transect lines as x and y axis then generate random coordinates. Use a quadrat at those coordinates to count number of individuals of each species. Use an identification key and sample at different times of the year.