biodiversity

• species


  a group of organisms that can freely breed to produce fertile offspring, very similar in appearance
• habitat


  where an organism lives, specific locality with a specific set of conditions
• population 


  group of organisms of the same species in a given location
• community

  all the living organisms, of all species, living together in the same place at the same time
• ecosystem


  self contained system including all living organisms and their environment interacting with each other
• biodiversity 


  measure of the variation found in the living world
• habitat diversity 


  number of habitats in an area
• species diversity 


  number of species and abundance of each species
• species richness 


  total number of species
• species evenness

  abundance of each species
• genetic diversity


  the variation between individuals of the same species
• random sampling


  selecting individuals by chance, avoids bias but may not cover all areas and species so underestimate of biodiversity
• types of non random sampling

  opportunistic, stratified, systematic
• opportunistic sampling 


  based on prior knowledge, deliberately choose areas so may be biased leading to overestimation
• stratified sampling 


  divide habitats into areas that appear different , ensures each section is represented, can lead to over representation
• systematic sampling


  samples taken at fixed intervals e.g line and belt transects
• prep for sampling plants

  • large number of samples -> reliability
  • consistent approach
  • keys to identify organisms
  • repeat at different times of year
• visual survey of habitat

  • count larger plants and trees
  • note infrequent plants
• quadrats in random sampling


  • divide area into grid and choose random coordinates
  • place quadrat on coordinate
  • measure abundance of plant species

  1. abundance scale e.g ACFOR
  2. estimate percentage cover
  3. calculate percentage cover with point frame
• point frame


  used for percentage cover -> record plants touching the needle
• line transect 


  stretch a string/tape. count everything touching the line
• belt transect


  place quadrat along tape

  • continuous- flip quadrat over, no gaps
  • interrupted- quadrat at set intervals
• observations when sampling animals

  • footprints
  • droppings
  • burrows
• tree beating

  dislodge small animals from the tree -> fall onto white sheet for identifying
• sweep net


  sweep net in wide areas and empty onto sheet -> suitable for low vegetation/ aquatic habitats
• pooter


  collects animals before they fly away -> used with tree beating and sweep net
• pitfall trap


  used to collect crawling orgnanisms -> should contain water to prevent escape
• tullgren funnel


  used to collect small animals from leaf litter

  lap heats and dried litter -> animals move down through mesh into pot
• light trap

  used to collect flying insects at night -> UV lamp attracts insects
• longworth mammal trap


  enter tunnel, trip door and become trapped -> not harmful, checked regularly

  used with mark + recapture technique
• estimating population size

  • catch first sample = C1
  • mark and release
  • catch a second sample = C2
  • number marked + recaptured = C3
• mark + recapture equation

  (C1 x C2)/ C3
• why calculate biodiveristy


  the stability of an ecosytem is proportional to its biodiveristy

  important in conservation and environmental management
• simpsons diversity index


  measure of the diversity of a habitat -> takes into account both species evenness and richness
• when D= 1

  • high level of diversity
  • stable habitat
• when D=0

  • low level of diversity
  • dominated by 1 species
  • habitat easily damaged by changed
• measuring genetic diversity


  important in determining conservation status -> isolated populations e.g captive breeding programs
• how to measure genetic diversity

  measure polymorphism
• locus


  position of a gene on a chromosome
• polymorphic gene loci


  a locus that has more than 2 alleles