biodiversity

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  • Created on: 29-05-13 00:06

Biodiversity

  • Species: group of similar organisms able to reproduce to give fertile offspring
  • Habitat: area inhabited by a species, including physical factors (soil, temp.) and living biotic factors (availability of food, presence of predators)
  • Biodiversity: variety of living organisms in an area
    • Habitat diversity: no. of different habitats in an area e.g. coastal has beaches, sand dunes, salt marshes
    • Species diversity: no. of different species and abundance of each in an area
    • Genetic diversity: variation of alleles within species or population of species
  • Species richness: number of different species in an area. The higher the number of species, the greater the species richness. It is measured by taking random samples of a habitat and counting the number of species.
  • Species evenness: measure of the relative abundance of each species in an area. The more similar the population size of each species, the greater the species evenness. It is measured by taking random samples of a habitat, and counting the number of individuals of each different species.
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Biodiversity 2

  • Choose an area within habitat to sample
  • Count number of individuals of each species
    • Plants: use quadrat, point frame, transect
    • Flying Insects: sweepnet, white sheet and stout stick
    • Ground Insects: pitfall trap, tullgren funnel, light trap
    • Aquatic Animals: net
  • Repeat process to take as many samples as possible, better indicant of whole habitat
  • Use results to estimate total no. of individuals or total no. of different species in habitat
  • Diversity is measured using Simpson's Index of Diversity
  • Simpson's index of diversity takes into account both species richness and evenness
  • D = 1 - (sum of (n/N)^2)
    • n = total number of individuals of one species
    • N = total number of organisms of all species
  • Closer to 1 the index is, the more diverse the habitat.
  • Greater the species richness and evenness, the greater the number.
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