Biodiversity

• Biodiversity is the measure of all living organisms worldwide and the variation between them.
• Levels of biodiversity

  >Habitat diversity: the range of habitats in which species live.

  Including sand dunes, woodlands, meadows and streams.

  >Species diversity: the richness and evenness of individual organisms that are similar in appearance and genetics.

  >Genetic diversity: the different breeds within a species.
• Why is sampling important?

  It measures the biodiversity of a habitat.

  Its important to sample the range of all organisms in a habitat to make sure all data collected is representative of this.
• Types of sampling - Random


  Sample sites inside a habitat are randomly selected using randomly generated co-ordinates or by selecting an area with a satellite map to find exact position.

  +) ensures data is not biased by selective sampling

  -) it can underestimate biodiversity as species with low presence may be missed
• Types of sampling - Opportunistic


  Researcher makes sampling decisions based on prior knowledge or during data collection process.

  +) easier and quicker than random sampling

  -) biased data as the researcher may be enticed by a larger species presence leading to an overestimate of biodiversity
• Types of sampling - Stratified 


  Dividing the habitat into areas that appear different and sampling them differently.

  +) All different areas of the habitat are sampled and all species are not under-represented as random sampling may miss certain areas

  -) May lead to over-representation of some areas in sample

  (i.e a disproportionate number of samples are taken in small areas that look different).
• Types of sampling - Systematic 


  When samples are taken at fixed intervals across the habitat. Includes techniques like line and belt transects.

  +) useful when habitat shows a clear gradient in some environmental factor. Ex. getting drier further away from a pond.

  -) underestimates biodiversity as only species on the line can be recorded so other species may be missed.
• Sampling plants pt.1

  >When collecting samples its important to consider how your presence will effect the surroundings.

  > You should know how to use a dichotomous key so that you can recognise all species correctly. Some plants also look different in different seasons so it may be necessary to visit the site multiple times to get a full estimate of the biodiversity there.
• Quadrats pt.1

  to locate position of quadrat you can count even paces till you have reached randomly selected coordinates or use a tape measure. To ensure no species inside the quadrat is underestimated, a grid with small squares can be used.
• Quadrats pt.2

  You can also lower a point frame into the quadrat and record any plant touching the needles. If the frame has 10 needles and is used 10 times then you will have 100 readings. It is important to record bare ground as it is east to bias your readings by using the frame non-randomly within the quadrat so its best to use it at regular intervals. (systematic sampling within the randomly placed quadrat).
• A Transect is a line taken across a habitat. Samples are taken along the line of tape.

  in a large habitat you can record all the plants that are touching the line at set intervals across it.

  >Interrupted belt transect - using a quadrat at set intervals along the line.

  >Contiinuous belt transect - using a quadrat beside the line and move it along the line to study a belt in detail to provide quantitative data.
• Sampling

  >By observation: noting presence of larger animals from footprints, burrows, damaged trees and droppings to estimate population size.

  >Collecting from trees: spread a white sheet under a branch and knock it with a stout stick. the vibrations dislodge small animals which drop onto the sheet and can be identified before they fly away.

  >Sweep netting: useful for low vegetation that isn't too woody and in water. with a stout net sweep through vegetation and small animals caught in net are emptied on a white sheet to identify. A pooter can collect small animals before they fly away.
• Sampling

  >Pitfall trap: container is buried in soil and catches small animals as they fall in after walking through plants of leaf litter. It contains water and scrunched paper to stop animals crawling out again and is sheltered from rain so it doesn't fill up.

  >Tullgren funnel: Leaf litter is placed in the funnel. Light from above the litter drives the animals downwards as it warms and dries up. They fall through a mesh screen to be collected in a jar underneath.

  A) light

  B) leaf litter

  C) funnel

  D) mesh

  E) funnel

  
• Sampling

  >Light traps: ultraviolet light is a collecting vessel containing alcohol. Insects are attracted to the light and fall into alcohol.

  >Kick sampling: kicking up gravels on the bed of the river and catching everything that is disturbed in a net.

  >Longworth trap: mark and recapture tecnique that estimates population sizes. first sample is captured and marked (C1) these are then released and traps left for a period of time. Second sample is captured (C2). The number of already marked species captured on second occasion is C3. The population size = (C1 X C2)/C3
• Species richness - the number of species found in a habitat. It is not sufficiently quantitative enough to be an indicator of biodiversity alone.

  Species evenness - the number of individuals in each species.
• Simpson's index of diversity

  Accounts for species richness and evenness.

  >A higher index indicates a higher presence of biodiversity which is stable enough to withstand changes to the environment.

  >A lower index indicates a lower presence of biodiversity meaning the habitat is dominated by a few species and a small change could damage the whole habitat.
• Genetic diversity is found when there is more than one allele for a particular locus which leads to variations between individuals that can be easily observed and more genetic differences between the gametes produced by members of the population.

  >Calculating the PERCENTAGE of loci in the population that have more than one allele.

  >Some loci have more than one allele and are known as polymorphic gene loci which increases genetic diversity.

  A) number of polymorphic gene loci

  B) total number of loci

  
• Genetic variations may be hard to identify as some may have recessive alleles which are difficult to locate as those who carry them don't always express the traits.
• Allele is a version of a gene.

  Locus is the position of that gene on a chromosome.

  Polymorphic gene locus is a locus that has more than two alleles.
• Suitable Populations to calculate genetic diversity include zoos with captive breeding programmes, rare breeds and pedigree animals.
• Factors affecting biodiversity - human population growth

  Population growth:

  • demands more food and consumer goods
  • alters ecosystems
  • destroys habitats for land and natural resources
  • pollutes atmosphere
  • causes extinction
• Factors affecting biodiversity - agriculture

  >clearing vegetation for farming space reduces sizes of habitats and populations of species reducing genetic diversity reduces the capacity for species to adapt to changing conditions through evolutions.

  >using monoculture increase efficiency of yield and reduces genetic diversity.

  >selective breeding reduces genetic diversity as farmers select particular traits of crops, such as high protein content and other breeds die out.
• Factors affecting biodiversity - climate change

  > As climate changes in rainfall and temperature, species cannot adapt leading to the migration of populations towards the poles. Obstruction to these migrations include: large bodies of water, mountain ranges and large human developments.

  > Selectively bred agricultural crops are unlikely to be able to adapt to changing conditions and are vulnerable to disease. Efficiency of agriculture will decline and less food will be available to the population.

  > Extinction
• Ecological reasons to maintain biodiversity

  >Maintain the interdependence of organisms.

  habitats with a higher species diversity are more stable and can withstand certain amounts of change.

  >To prevent the decline of keystone species which would have dramatic effect on their environment.

  Ex. predators that limit population of herbivores so vegetation is not overgrown
• Genetic reasons to maintain biodiversity

  When biodiversity declines, genetic diversity decreases.

  >Maintaining genetic resource of wild species is essential due to the potential existing in species today.

  >By selection and breeding from wild strains and species we can breed new crop varieties that cope with changes to climate.

  >Genetic engineering uses evolved molecules from plants and fungi for pharmaceutical products to combat diseases.
• Economic reasons to maintain biodiversity

  >use natural resources for infrastructure

  >regulation of climate and atmosphere

  >soil depletion as a result of decreased biodiversity which are subjected to continuous monoculture become less fertile, reducing agricultural yields as the same crops take up the same minerals which are lost when harvested.
• Aesthetic reasons to maintain biodiversity

  Landscapes are important for mental and physical wealth

  Living biosphere has effect on the landscape: trees protect soils from intense sunlight

  Deforestation exposes this soil and changes landscapes
• Conserving biodiversity

  > In situ conservation: conserving species in their natural habitat

  > Ex situ conservation: conserving endangered species by activities that take place outside its normal habitat
• Methods of In situ conservation

  > Legislation: pass laws that stop activities like hunting, logging and land clearing for agriculture / human developments.

  > National parks: protect areas for 'sites of scientific interest' and create marine conservation zones.
• Methods of in situ conservation

  > Wildlife reserves with good environmental conditions, living space and representativeness for species.

  Reserve should meet needs for indigenous activity.

  .there may be conflict due to:

  -protected animals raiding their crops

  -people continuing to poach

  -tourists feeding animals and litter

  -illegal logging

  >reserves also protect natural resources, geology and soils.
• Advantages of in situ conservation

  • protects biodiversity and representative ecosystems
  • protects elements of cultural and natural heritage
  • facilitates scientific research
  • opportunities for ecologically sustainable land uses
• Disadvantages of ex situ conservation

  • population may have lost most of its genetic diversity
  • endangered habitats may not be large enough to ensure survival of species
  • area can attract poachers
  • endangered conditions that caused damage may still be present
• Methods of Ex situ conservation

  >Seed banks: Contain seeds that remain viable for decades to conserve biodiversity in future

  provide seeds for food crops and disease resistant crops for agriculture

  can be used for habitat reclamation if one is destroyed
• Methods of Ex situ conservation - Bontanic gardens

  +) seeds can be collected from habitats without causing much disturbance

  +) stored in large numbers without occupying too much space

  +) reproduce asexually

  -) funding is difficult

  -) collected samples may not have a representative level of genetic diversity

  -) plants that reproduce asexually are genetically identical which reduces genetic diversity
• Methods of Ex situ conservation - zoos

  >Involves captive breeding of endangered animals.

  >Freezing sperms, eggs and embryos preserves genetic material.

  +) organisms protected from poachers and predators

  +) genetic diversity of population can be preserved

  +) education and research

  +) health of individuals can be monitored and treated

  -) limited genetic diversity

  -) organisms live outside their habitat - moral objections

  -) expensive to maintain

  -) animals exposed to wider range of diseases
• International conservation agreements to protect species and habitats

  CITES - Ensure international trade in specimens of wildlife does not threaten their survival.

  Agreed in 1973. Aims to

  • monitor international trade in selected species of plants and animals
  • ensure trade in wild plants for commercial purposes is prohibited
  • ensure trade does not endanger the survival of populations in the wild
• International conservation agreements to protect species and habitats

  CRB - Rio's conservation of biological diversity.

  Conserve flora, fauna, natural resources, clean air, shelter and medicine.

  Signed in 1992.

  Co-operation between countries

  Aims to:

  • conservation of biological diversity
  • sustainable use of its components
  • shared access to genetic resources
  • transfer of scientific knowledge and research
  • fair distribution of benefits arising from use of genetic resources
• Local conservation agreements to protect species and habitats

  CSS - countryside stewardship scheme

  Agreed in 1991

  Local governments pay farmers to conserve english landscapes

  • improves natural beauty and diversity of the countryside
  • restores historical features and habitats

  Replaced by the environmental stewardship scheme in 2005 and aims to:

  • look after wildlife species in their habitats
  • conserve crops and livestock
• Monoculture crops cause genetic erosion