Topic 11

• Different levels at which biodiversity can be measured

  Habitat biodiversity, genetic biodiversity, species biodiversity
• Habitat biodiversity


  Number of different habitats found within an area
• Species biodiversity


  Made of species richness and evenness
• Species richness


  Number of different species living in a particular area
• Species evenness


  Comparison of the number of individuals of each species living in a community
• Community


  All the populations of living organisms in a particular habitat
• Genetic biodiversity


  Variety of genes that make up a species
• Sampling


  Taking measurements of a limited number of individual organisms present in a particular area
• Uses of sampling


  To estimate the number of organisms in an organism, to measure a particular characteristic of an organism
• Types of sampling


  Random, non-random
• Random sampling


  Selecting individuals by chance, each individual has an equal likelihood of selection
• How to carry out a random sample

  Make grid with tape measures, use random numbers to determine x coordinate and y coordinate, take sample at each coordinate pair
• Types of non-random sampling


  Opportunistic, stratified, systematic
• Opportunistic sampling


  Using organisms that are readily available
• Weakest form of non-random sampling


  Opportunistic
• Why is opportunistic sampling the weakest form of non-random sampling?


  Not representative
• Stratified sampling


  Dividing a population into strata based on a characteristic, random sample taken from each strata proportional to size
• Systematic sampling


  Identifying different areas within an overall habitat which are then sampled separately (Transects)
• Line transect


  Marking a line along the ground between the poles and taking samples at specific points
• Belt transect


  Two parallel lines marked, samples taken of the area between the two lines
• Why is a sample never truly representative?

  Sampling bias, chance
• How to reduce sampling bias

  Random sampling
• How to reduce effect of chance

  Large sample size
• Sampling methods


  Pooters, sweep nets, pitfall traps, tree beating, kick sampling, quadrats
• Types of quadrats


  Point, frame
• Point quadrats


  Frame containing a horizontal bar, long pins can be pushed through the bar, each species of plant that the pin touches is recorded
• Frame quadrats


  Square frame divided into grid of equal sections, type and number of species within each section is recorded
• How to measure species richness


  Use sampling method, compile list of species identify, keys used to identify species
• Different things you can measure with frame quadrats


  Density, frequency, percentage cover
• How to do capture-mark-release-recapture


  Capture as many individuals of a species as possible, organisms marked and released, time is allowed for organisms to redistribute, another sample collected, compare number marked and unmarked in second sample, if lots are marked you have a small sample
• How to measure species evenness using capture-mark-release-recapture


  Compare the total number if each organism present
• Simpson's Index of Biodiversity


  Measure of biodiversity that takes species richness and evenness into account
• Formula for Simpson's Index of Biodiversity


  1- (Sum of total number of organisms of a particular species/ Sum of total number of organisms of all species)^2
• What a low biodiversity index means


  Few successful species, extreme nature, fewer ecological niches, very specific adaptations, relatively simple food webs, change to the environment has a major effect on the ecosystem
• What a high biodiversity index means


  Large number of successful species, more ecological niches, many species, complex food webs, change to the environment has a relatively small effect on the ecosystem
• Equation for proportion of polymorphic gene loci


  Proportion of polymorphic gene loci = Number of polymorphic gene loci/ Total number of loci
• Polymorphic genes


  Genes with more than one allele
• Suitable populations for measuring genetic biodiversity


  Zoos, rare breeds, pedigree animals
• Factors that affect genetic biodiversity


  Mutations, interbreeding
• Gene flow


  When an individual migrates from one population and breeds with a member of another population so alleles are transferred between two populations