4.2 Biodiversity

• Difference between species richness and species evenness

  1. Richness - number os species in a habitat
  2. Evenness - number of individuals in each species
  3. Both needed to reveal dominance - high biodiversity is associated with high number of species richness and evenness
• Different types of sampling

  1. Random - no particular system, aim is to be representative
  2. Opportunistic - take samples based on prior knowledge
  3. Stratified - population divided into smaller groups based on different characteristics and then sampled - may overrepresent
  4. Systematic - follow a pattern, fixed intervals with a transect. useful when habitats show a gradient, underestimate
• Why is sampling important

  • impossible to count every individual
  • sampling is representative and provides an estimate
• Simpson's index of diversity

  Measurement of the total number of organisms compared to the total number of organisms of each species. Low index of diversity = habitat is dominated by one species and the habitat is unstable as a change in this species can affect the whole habitat
• How can Simpson's Index be made more accurate

  • Random sampling
  • Key
  • Different seasons
• Conservation

  Protection and management of species and habitats in order to maintain biodiversity. In-situ (in the habitat), ex-situ (outside habitat)
• Conserving seeds rather than adult plants

  • can be collected with minimal damages to the habitat
  • take up little space
  • lower maintenance
  • Cheaper to transport
  • Less susceptible to disease
• unbiased sampling method

  1. Use quadrants
  2. Random sampling (number generator)
  3. Place measuring tape/grids at regular intervals
  4. calculate percentage coverage to determine abundance
  5. repeat - maybe in a different season
• Why is it inaccurate to estimate the total number of species in the world

  1. Some habitats inaccessible
  2. May have become extinct
  3. Evolution still ongoing
  4. Might mistake several species for one
• Polymorphism

  • Gene has more than one allele such as hair colour, eye colour and blood type
• Monomorphism

  Gene has one allele. most genes monomorphic. basic structure of species is similar
• How to calculate the proportion of polymorphic gene loci

  $\frac{number\ of\ polymorphic\ gene\ loci}{total\ number\ of\ loci}$
• Maintaining biodiversity

  1. Aesthetic - tourism and mental health
  2. Economy - monoculture can leach nutrients from the soil and cause crops to have lower yield. Crop rotation can help avoid this. cutting down trees causes instability on sloping group and increased risk of landslides
  3. Ecological - minimises disruption to food chains and nutrient cycles. protect key species who's extinction would affect other species essential to repent collapse of ecosystem
• How to maintain biodiversity

  In Situ

  • inside their habitat; manitains diversity and evolutionary and interdependent relationships
  • not always possible as it may be unsafe, numbers low they might just die out and habitat destroyed
  • Wildlife reserves - protected areas, control poaching and human access
• Maintain biodiversity

  Ex Situ

  • not in natural habitat
  • zoos/botanical gardens
  • captive breeding - in human controlled environments. bad - small humber of mating partners to choose from, less resistant to disease and changes to behaviour
• Conservation Agreements

  1. CITES - not killing endangered species and limiting trade by licensing
  2. Rio Convention on biological diversity (CBD) - using plant and animal products in a sustainable way, everyones responsibility, provides guidance
  3. Countryside Stewardship Scheme (CSS) - improve and extend wildlife habitats, promote land management
• Habitat biodiversity

  • range of different ecosystems or habitats in a particular region
  • large number of habitats = high biodiversity (woodlands and meadows)
  • Sandy deserts have low biodiversity - conditions same
• Genetic diversity

  • diversity of alleles and genes in the genome
  • can be present between populations of the same species (different selection pressures)
  • single population; helps population adapt and survive changes in the environment
• Factors affecting biodiversity

  1. Human population growth

  • more forest cleared for housing and food production.
  • pollution and waste production puts further burden on fragile ecosystems
  • Transmission of disease between species
• Factors affecting biodiversity

  2. Agriculture/monoculture

  • more efficient to grow crops, farms have fields set aside for growing one crop species
  • Monoculture reduces biodiversity - may be less resistant to disease
• Factors affecting biodiversity

  Climate change

  • habitat loss, animals migrate
  • species and populations may be directly destroyed decreasing the gene pool available for selection and evolution
  • too fast for species to adapt to new conditions - extinction