Part 2

• EXTINCTION


  when a species no longer exists

  20% all species extinct by 2030

  50% all species extinct by 2100
• ENDANGERED


  population critically low, due to humans, so species likely to go extinct

  33% primates are endangered
• CRITICALLY ENDANGERED


  a species is likely to go extinct as numbers are not sustainable and too low for the survival of the species
• How do humans reduce biodiversity?

  - population increase

  - increase in pollution

  - killing animals for protection (ANOPHELES MOSQUITO)
• Human influence on BIODIVERSITY: main problems a result of:

  DEFORESTATION: permanent removal of large areas of forest to provide wood for building and fuel, as well as providing space for buildings, roads and agriculture

  AGRICULTURE: large amount of land need to be cleared and farmed to feed the growing population. OFTEN A SINGLE CROP IS GROWN: MONOCULTURE

  CLIMATE CHANGE: evidence shows that greenhouse gases (CO2 (from burning fuels/methane) are increasing global temperatures
• DEFORESTATION


  habitat destruction used for: roads, buildings, houses, industry

  HOW IS REDUCES BIODIVERSITY:

  • directly reduces the number of trees in an area
  • if a specific type of tree is felled, it reduces species diversity
  • reduces the number of animals present in an area, due to the destruction of their habitat/food source
  • animals are forced to migrate to other areas in order to survive
• how does AGRICULTURE reduce biodiversity

  - removal of hedgerows to allow farmers to use large machinery and free up land. This reduces the number of plant species present in an area, thus destroys the habitat of animals such as mice/blackbirds

  USE OF CHEMICALS - PESTICIDES/HERBICIDES

  MONOCULTURE
• How do PESTICIDES reduce biodiversity?

  indiscriminate spraying of pesticides REDUCES SPECIES DIVERSITY as it kills pests (usually insects) indirectly kills the food source of other organisms

  KILLS OTHER SPECIES AND AFFECTS FOOD WEBS/CHAINS

  Can cause harm to humans due to the bio-accumulation of food webs
• How do HERBICIDES reduce biodiversity?

  reduces species diversity due to removing weeds and killing vital food sources
• What is MONOCULTURE?


  Growing a single type of crop in an area
• How does MONOCULTURE reduce biodiversity?

  has an enormous LOCAL effect by lowering biodiversity, as only one specific plant species is grown and present, supporting only a few animal species
• why are HEDGEROWS good?

  - provide food and shelter to important species

  - pollination of crops by insects

  - control water levels and run off

  - pest control - PREDATORS LIVE IN THEM
• What reduces genetic variation?

  - clearing land

  - monoculture

  - selective breeding

  - cloning
• what is the GREENHOUSE effect?

  sun/heat hits the earth and is reflected back with a longer wavelength, so some gets reflected again by the atmosphere
• what is making GREENHOUSE effect worse?

  - deforestation (removing trees which remove carbon dioxide)

  - burning fossil fuels (release carbon dioxide)

  - cattle/rice fields (produce methane)

  • CONTRIBUTE THE GLOBAL WARMING
• How does CLIMATE CHANGE reduce biodiversity?

  MELTING OF POLAR ICE CAPS - could lead to the extinction of the few plant and animal species that live in these regions

  • RISING SEA LEVELS
  • HIGH TEMPERATURES, LOW RAINFALL
  • INSECT LIFE CYCLE AND POPULATION CHANGES
• what are the effects of RISING SEA LEVELS?

  COULD LEAD TO:

  • FLOODING of low-land areas, resulting in a lower number of terrestrial habitats
  • SEA WATER FLOWING UP RIVERS: leads to the loss of habitat for some freshwater plant and animal species
• how can HIGH TEMPERATURES and LOW RAINFALL reduce biodiversity?

  - could lead to some plant species failing to survive, resulting in drought-resistant species to become dominant, leading to the loss of animal species
• how can INSECT LIFE CYCLE AND POPULATION CHANGES reduce biodiversity?

  Insects are key pollinators, so if the range of insects changes, this could affect the lives of the plants that they leave behind, resulting in extinction
• CONSEQUENCES on CLIMATE CHANGE on BIODIVERSITY on the SPREAD OF DISEASE:

  Main:

  • diseases of domestic animals will increase - blue tongue in cattle will spread through Britain due to the midge carrying the disease surviving in winter
  • INSECT PESTS of CROP PLANTS and PLANT DISEASES such as FUNGAL INFECTIONS normally killed by frost will survive the milder winter conditions
  • Female vector Anopheles mosquitoes will spread a parasite (plasmodium) onto humans when they feed - CANNOT FUNCTION BELOW 10 DEGREES AND NEED HIGH HUMIDITY
• Other consequences of climate change

  MANGROVE SWAMPS

  • rely on their roots being out of water in order to obtain oxygen
  • if sea levels rise, mangrove swamps will be lost

  FISH

  • some species of fish stop growing once a certain temperature is reached
  • could stop growing before they are of reproductive age or before they are of sufficient weight to survive the winter

  CHANGE IN RAINFALL PATTERNS:

  • climate change results in an increase in rainfall in some areas but decrease is others
  • SELECTIVE BREEDING results in low genetic variation so cannot adapt to change in rainfall patterns
• REASONS for maintaining biodiversity (5)

  - aesthetic reasons

  - economical reasons

  - ecological reasons

  - ORGANISMS HAVE THE RIGHT TO EXIST

  - SPECIFIC RELIGIOUS REASONS
• AESTHETIC REASONS FOR MAINTAINING BIODIVERSITY

  ENRICHMENT OF LIVES

  • relaxing on a beach
  • walking through woodland

  PROVIDES INSPIRATION FOR PEOPLE

  • musicians/writers

  PEOPLE RECOVER MORE RAPIDLY FROM INJURY/STRESS when supported by plants/natural environment
• ECONOMIC REASONS: first one:

  • soil erosion and desertification as a result of deforestation:
  • Reduces a country's ability to grow own crops
  • Reliance on other countries to import
• Species with potential economic/chemical/medical value

  • Will go extinct before being discovered
• Non-sustainable removal of resources (timber)


  Leads to collapse in industry in that area
• Eco-tourism

  • Areas that are biodiverse/attractive/pleasing promote tourism
  • Provides jobs/money to local community
• Continuous Monoculture


  • Results in soil depletion of mineral ions
  • Plants are more vulnerable to plant/insect/microorganism competition
  • Farmers spend money on pest/herbicides and fertilisers
• Plant variety

  • Need for cross breeding
  • Leads to better characteristics (disease resistance/increased yield)
• High biodiversity


  Provides protection against abiotic stresses (climate change, natural disasters/disease)

  A change in conditions/disease could destroy a crop (waste of money)
• Greater diversity

  • Greater potential to manufacture different products in the future
  • Provides jobs and makes money
• ECOLOGICAL REASONS


  organisms are part of a food chain and are interdependent on others for survival (FOOD SOURCE, HABITAT, POLLINATORS)

  Keystone species

  • species that have a key role in maintaining the structure of an ecological community.
  • HAVE A DISPROPORTINALLY LARGE EFFECT ON THEIR ENVIRONMENT; if removed, their habitat drastically changes

  Genetic variation leads to EVOLUTION by NATURAL SELECTION

  • genetic variation allows organisms to adapt to changes in the environment:
  • CLIMATE CHANGE
  • INCREASED POLLUTION LEVELS
  • EMERGENCE OF A NEW DISEASE
  • ARRIVAL OF A NEW PEST
• Key stone species DEFINITION

  species that play a key role in maintaining the structure of an ecological community

  HAVE A DISPROPORTIONALLY LARGE EFFECT ON THEIR ENVIRONMENT, SO IF REMOVED, HABITAT WILL DRASTICALLY CHANGE
• two examples of KEYSTONE SPECIES

  prairie dogs

  sea stars
• how are PRARIE DOGS keystone species?

  up to 200 species rely on them

  • provide food source
  • provide burrows for other animals (SNAKES)
  • tunnelling aerates soil, poo adds nutrients to soil
• how are SEA STARS keystone species?

  a predator

  • maintain a balanced ecosystem by eating MUSSELS and SEA URCHINS, which have no other natural predator

  WHEN REMOVED:

  • huge increase in mussels, reducing the number of other species present in the area
  • growing population of SEA URCHINS crowd coral reefs, preventing other species occupying the same area
• What is IN-SITU


  conservation of a species in its natural habitat

  • WILDLIFE RESERVES
  • MARINE CONSERVATION ZONES
• ADVANTAGES of In-Situ


  4 advantages

  • Conservation of habitat, along with all organisms within the habitat
  • Biodiversity of whole area is maintained
  • Cheaper as just needs managing
  • Allows evolution to continue
• DISADVANTAGES of In-Situ


  5 problems

  • Large amounts of land needed; more difficult to manage large areas of land (COULD CROSS BORDERS CAUSING CONFLICT)
  • Local people may still hunt animals or harvest plants/timber from environment
  • Difficult to manage flooding, fires, disease
  • Animals may leave reserve, causing problems for local people
  • Nowhere for animals to go if climate change occurs
• In Situ reserves in the UK

  - 24 National Parks - preserve biodiversity, landscapes, geology, natural resources, cultural heritage

  - 224 NNR (national nature reserves)

  - 6000 SSSI (sites of special scientific interest)

  - 1500 LNR (local nature reserves)