4. Biodiversity, Evolution + Disease

• Habitat biodiversity


  variety of habitat in an area/ecosystem

  more habitats result in more niches, which encourages species biodiversity
• Species biodiversity


  represents the number of different species living in an area
• Species richness


  number of different species present in a particular ecosystem/area
• Species evenness


  measure of relative abundance of individuals in each species of an area/ecosystem
• Genetic biodiversity


  the variety of alleles in a species/population
• Intraspecies Variation


  variation within a species
• Interspecies Variation


  variation between species
• How can you observe genetic variation?

  sequence of DNA, sequence of mRNA, sequence of amino acids
• What is diversity/variation caused by?

  genetic & environmental differences
• What are the advantages of a sample?

  Impossible to sample entire population

  Cheaper & quicker to take sample
• Why is a large sample size needed?

  representative data produced

  necessary to perform statistical tests
• Random sample?


  - Random number generator for coordinates of quadrat on transect
• Advantage and disadvantages of a random sample?

  A = no bias

  D = not representative and may over/under-estimate popualtions
• Opportunistic sampling?


  - Based on prior knowledge/data collection

  - Areas with particular species
• Advantage and disadvantages of an opportunistic sample?

  A = easy and quick

  D = biased data
• Stratified sampling?


  - Divide habitat into strata

  - Sample based on proportion present in overall population
• Advantage and disadvantages of a stratified sample?

  A = representative of all areas

  D = disproportionate samples
• Systematic sample?


  - sample taken at fixed intervals across a habitat e.g., belt/line transect
• Advantage and disadvantages of a systematic sample?

  A = useful when environment shows a clear gradient

  D = only species on line/belt transect recorded so unrepresentative
• Types of traps?


  Pitfall trap - small container in soil, little water, crumpled paper as lid

  Tullgreen funnel - leaf litter, light, insects fall through mesh into jar

  Light trap - ultraviolet light attracts insects, fall into collecting vessels with alcohol

  Longworth trap - humane, regularly monitored, measure population size with mark and recapture technique
• Calculation for population size with mark and recapture technique?

  (C1 x C2) / C3 = total population
• What does standard deviation measure?

  average variation of data from the calculated mean
• proportion of polymorphic gene loci calculation


  Number of polymorphic gene loci/total number of loci

  
  

  - provides measure of genetic diversity
• polymorphic gene loci


  A polymorphic loci has 2 or more alleles
• What affects biodiversity?


  - Human population growth

  - Agriculture e.g., monocultures, deforestation

  - Climate change

  - Extinction
• Affects of human population growth?

  - Learned to use environment for our advantage

  - Alter ecosystems to provide ourselves with food

  - Use more and more of the Earth's resources

  - We pollute the atmosphere
• Affects of agriculture?


  - Clearing areas reduces habitat and population size of species

  - Reduces genetic diversity

  - Isolated and fragmented populations, too small to survive

  - Monocultures and selective breeding leads to genetic erosion
• What are monocultures?


  - Crop consisting of one strain of a species

  - Dependence on a single agricultural commodity

  - Vulnerable to change in environment due to lack of genetic variation
• Affects of climate change?

  - Species who have lost genetic diversity find it harder to adapt

  - Migrate according to climate patterns

  - Obstructions to migration e.g., major human developments, agricultural land, large bodies of water and mountain ranges

  - Also affects crops
• What is extinction?


  The permanent loss of all members of a species.
• Ecological reasons for maintaining biodiversity

  - Interdependence of species maintained

  - Maintaining the food chain

  - Protect keystone species
• What are keystone species?

  A species that has a disproportionately large effect on its environment relative to its abundance.
• How does biodiversity act as a genetic resource?

  - Careful selection and breeding from wild strains/species can help crops evolve to section pressures e.g., climate change

  - Genetic engineering produces transgenic species

  - Potential new medicine and vaccines to be found
• Economic reasons for maintaining biodiversity?

  - Regulation of atmosphere and climate

  - Purification and retention of fresh water

  - Formation and fertilisation of soil

  - Recycling of nutrients

  - Detoxification and and recycling of wastes

  - Crop pollution

  - Growth of timber, food and fuel

  - Discovery of potential medicines
• Aesthetic reasons to maintain biodiversity?

  - Patients recover more rapidly when exposed to nature

  - Important for well-being and health

  - Tropical forests protect soil from being eroded and washed away by rainfall

  - Organic matter in soil holds water for trees, reducing run-off and drainage

  - Deforestation leads to severe flooding
• in situ conservation


  - Conservation in natural habitat

  - Minimise human impact and protect natural environment
• Exsitu conservation


  - involves raising and breeding animals outside of their environment
• Examples of in situ conservation


  - marine conservation zones

  - local nature reserves

  - wildlife reserves

  - national parks

  - SSSIs
• Examples of ex situ conservation

  - captive breeding programmes

  - zoos

  - seed banks

  - botanic gardens
• Advantages of in situ conservation

  - natural environment

  - permanent protection of biodiversity

  - permanently protection of natural and cultural heritage

  - provide opportunity for ecologically sustainable land use

  - ecological integrity is maintained

  - facilitates scientific research