Module 4.2.1- Biodiversity

Cards (62)

  • Biodiversity
    the variety of living organisms present in an area
  • Habitat biodiversity
    the number of different habitats found within an area
  • The greater the habitat biodiversity...

    the greater the species biodiversity will be within that area
  • Species richness
    The number of different species living in a particular area
  • Species evenness
    the relative proportion of different species in a given area
  • Genetic biodiversity
    refers to the variety of genes that make up a species
  • Sampling
    can be used to estimate the number of organisms in an area without having to count them all
  • Random sampling
    a sample that fairly represents a population because each member has an equal chance of inclusion
  • How can you take a random sample- example
    1) mark out a grid on the grass using 2 tape measures at right angles
    2) use random numbers to determine the x-coordinate and y-coordinate on your grid
    3) take a sample at each of the coordinate pairs generated
  • Non-random sampling
    an alternative sampling method to random sampling, where the sample is not chosen at random. It can be opportunistic, stratified or systematic.
  • Opportunistic sampling (NRS)

    sampling using the organisms that are conveniently available. The weakest form of sampling as it may not be representative of the population.
  • Stratified sampling (NRS)

    the population is divided into a number of strata (subgroups) and weighted based on a particular characteristic.
    e.g. divided into male and female.
    then random sampling used for that
  • Systematic sampling (NRS)

    select some starting point and then select every kth element in the population
  • Line transect- systematic sampling

    a line is marked along the ground and samples are taken at specified points.
  • Belt transect- systematic sampling
    2 parallel lines are marked, and samples are taken of the area between the two lines
  • Sampling bias
    A problem that occurs when a sample is not representative of the population from which it is drawn. for example choosing more interesting looking flowers in an area.
  • Chance
    the organisms selected may, by chance, not be representative of the whole population.The larger the sample size, the more reliable the result
  • Pooters- sampling technique
    used to catch small insects. suck on a mouthpiece and insects are drawn into the holding chamber via the inlet tube. There is a filter before the mouthpiece to prevent it being sucked into the mouth.
  • Sweep nets- sampling technique

    used to catch insects in areas of long grass
  • Pitfall traps- sampling technique

    used to catch small, crawling invertebrates. a hole is dug in the ground which insects fall into with roof
    left overnight
  • Tree beating - sampling technique

    used to take samples of the invertebrates living in a tree or bush large white cloth is stretched out under the tree
    the tree is shaken/beaten to dislodge the invertebrates onto the cloth
  • Kick sampling- sampling technique

    used to study organisms living in a river. the river bank or bed is 'kicked' for a period of time to disturb the substrate
    a net is held just downstream for a set period of time in order to capture any organisms released into the flowing water
  • Point quadrat (Plant sampling)

    a frame has a horizontal bar - set intervals along the bar long pins can be pushed through the bar to reach the ground, each plant that touches the pin is recorded
  • Frame quadrat (Plant sampling)

    consists of a square frame divided into a grid of equal sectionsthe type and number of species within each section of the quadrat is recorded
  • Measuring species richness
    Various techniques should be used to compile list of species in habitat. Then total is a measure of species richness
  • Measuring species evenness
    Ratios of organisms in a community.
    Example:
    50 organisms under a log
    20 woodlice
    15 spiders
    15 centipedes
    This is even
    45 woodlice
    5 spiders
    This is uneven
  • Frame quadrat- density
    count the number of individual large plants in a 1m x 1m square quadrat. this gives you the density per square meter. it is an absolute measure.
  • Frame quadrat- frequency
    using the small grids within a quadrat, count the number of squares a particular species is present in.
  • Frame quadrat- percentage cover
    It is an estimate by eye of the area within a quadrat that a particular plant species covers
    it is fast
  • 2 ways to increase reliability

    take a larger sample size
    calculate mean
  • Estimating animal population size: capture-mark-release-recapture method
    compare numbers of marked individuals with number of unmarked in the second sample and then the population size can therefore be estimated
    the greater the number of marked individuals recaptured, the smaller the population
    species evenness can then be calculated
  • Abiotic factors
    a nonliving condition or thing, as climate or habitat, that influences or affects an ecosystem and the organisms in it
  • Examples of abiotic factors

    wind speed
    light intensity
    relative humidity
    pH
    temperature
    oxygen content in water
  • How to calculate biodiversity
    Simpson's index of diversity
  • Simpson's index of diversity
    a measure of biodiversity that takes into account both species richness and species evenness
    a higher value means there is more diversity
  • Species diversity
    takes into account both the number of different species present (species richness) and the number of individuals of each species
  • Importance of genetic diversity
    Diverse gene pool gives a population more flexibility to survive in a changing environment and is less likely to become extinct
    The more genetically diverse a population, the more ways it has to adapt
  • Factors that increase genetic diversity

    mutation
    interbreeding between different populations (gene flow)
  • Factors that decrease genetic diversity

    selective breeding (artificial selection)
    captive breeding programmes are breeds artificial cloning
    natural selection
    genetic bottlenecks
    founder effect
    genetic drift
  • Polymorphism
    the existence of two or more forms of individuals within the same animal species (independent of sex differences)