biodiversity

• species richness -

  • Number of different species in the habitat
  • Qualitative measurement
• species evenness -

  • relative abundance of individual species
  • quantitative measurement
• • Species richness is greatest at the equator and the tropics due to favourable abiotic factors
  • Species richness tapers off at the poles
  • There are species richness hotspots (more often than not these are nearer the coasts)
• endemic species -

  • A species only found in one geographical location
  • High level of endemism is linked to high level of biodiversity
• • species evenness also termed relative species abundance
  • Not just the number of organisms but also their spread across an ecosystem
• The diversity index takes both species richness and species abundance into account

  • D = diversity of habitat
  • Σ = sum of
  • n = the total number of organisms of a particular species (or percentage cover)
  • N = the total number of organisms of all species (or total % cover)

  
• • Biodiversity within a species is measured by DNA analysis
  • •Allelic frequencies = how often a particular gene/allele occurs in a population
• Ethical reasons for preserving biodiversity -

  • Future generations cannot enjoy the beauty of environments and variety of animals
  • Extinction loses that genetic code forever
  • Mass extinctions caused by indirect human activities (i.e. climate change) are harmful to all organisms
• Economic reasons for preserving biodiversity -

  • Storm Desmond caused £500million
  • Flooding over the 2016 Christmas period estimated £5 billion
  • Netherlands population = 17 million