• The variety of living species
• The degree of nature’s variety
• It allows for the permanent stability of an ecosystem
• Involves an equilibrium between species. Biodiversity can be considered at different levels.
HABITAT
• Range of habitats
• Each may be occupied by different species
• Diverse habitats may lead to diverse species
• It is essential to conserve these
SPECIES
• Difference between species
• This could be within a habitat, or a community
• Differences could be structural or physical
• We can collect data about different species
• This will inform species richness
GENETIC
• Genetic variation exists within a species
• Degree of allelic variation between the members of a species
• It is good
o Lack of variation results in a lack of ability to adapt
o Natural selection depends on variation
SPECIES RICHNESS
• This is the number of different species present in a habitat
• The more species present, the richer the habitat
• Observe and record the species present in a habitat
• Samples should be taken
• Visual surveys should be taken, to ensure that nothing is missed
• However, this does not take into account the number of individuals of each species
• Not sufficient data to measure diversity alone
DIVERSITY INDEX
• Diversity index is a better way of describing biodiversity
• It takes into account both species richness and evenness
• Gives an idea of the number of each species relative to population size
• Small and large populations are treated differently
• The formula is: D = N(N-1)/n(n-1)
Where n = total number of organisms in each species And N = the total number of organisms of all species
HIGH INDEX OF BIODIVERSITY MEANS…
• Indicates a diverse habitat
• Many different species live there
• Small change to environment may only affect one species
• If this species is only small population, then only a small proportion of the habitat is effected
• Total effect on the habitat would be small
• Tends to be stable habitat
LOW INDEX OF BIODIVERSITY MEANS…
• Suggests it is dominated by few species
• Small change to the environment may affect one of the major species
• Could damage or destroy the whole species
• Small change would have a very large impact on the environment
• Much less stable environment
BENEFITS OF HAVING LARGE BIODIVERSITY
• Extinction reduces biodiversity
• Human clearing of land for agriculture removes habitats
• This increases chances of extinction
• Modern farming often plants only one type of crop (monoculture)
• Makes harvesting easier
• However, this has a very low diversity and reduces the variation of animals in this habitat
• Selective breeding is also used in agriculture, leading to genetic erosion
• •Genetic erosion reduces genetic diversity
• Prevents organisms from adapting to survive changes in their environment
MODERN FARMING AND BIODIVERSITY
• Deforestation = clearing forests for agriculture or buildings
• Reduces biodiversity
• Loss of habitat
• Destruction of species
• Change in microclimate
• Animals move away to habitats they are worse adapted to
• Disruption of complex food webs
CONSERVATION OF FORESTS IS SUSTAINABLE
• Deforestation creates space of agriculture but the land becomes infertile after a few years
• Cattle farming is not economically rewarding
• Conservation can generate income from eco-tourism
• The forests are a natural source of e.g. fruit, rubber
• Preservation of gene pools that come from conservation mean wild alleles are available to use in genetic engineering or selective breeding
• Tropical rainforests should be conserved to avoid:
o Loss in species and genetic diversity
o Disruption of food chains
o Loss of potential medicines
o Loss of wood/timber
o CO2 build-up in atmosphere contributing to global warming
o Leaching of ions in the soil
o Soil erosion
IN ORDER TO MEASURE BIODIVERSITY:
• All species must be observed
• Number of individuals must be counted Ideally this should be done for all organisms, however this may not always be practical. Instead, a habitat can be sampled.
Sampling is when a small, random portion of a habitat is selected and studied carefully. You can then multiply up the numbers of individual species found to give an estimate for the entire habitat.
Sampling allows us to:
• Study any impacts on the environment (EIA)
• EIA is used to estimate effects of a planned development on the environment
NUMBER OF SAMPLES
• Depends on the size of the habitat and time
• Number of samples should be sufficient to give an accurate measure of the number of species in habitat and relative abundance
• If two areas are being compared, the same number of samples should be taken at each
RANDOM SAMPLES
• Samples must be randomly chosen
• This avoids bias/subjectivity
• You must estimate the size of the habitat and decide where to take samples
• This can be done by:
o Taking samples at regular distances
o Use random numbers to plot co-ordinates
o Select co-ordinates from a map and use GPS to find the exact location
• However, this process may exclude infrequent plant
o You should visually survey the area
o Record any odd plants
o Write these down, but without abundance
o This is qualitative data
o It cannot be used for statistical analysis
SAMPLING PLANTS
• A square-frame quadrat can be used to define sample area
• Plant species are identified, then abundance is measured
• This is done by:
o ACFOR abundance scale
o Estimate percentage cover
o Key can be used to identify species within the quadrat
SAMPLING ANIMALS
• Sampling may disturb the habitat
• Animals may be frightened away – this would give an unrepresentative sample
• Animals must be trapped or caught, then an estimate made
• They can be caught by:
o Swamp Netting
o Collecting from trees
o Pitfall Trap
o Tullgren Funnel
o Light Trap
SPECIES RICHNESS
• This is the number of species present in a habitat
• The more species present, the richer the habitat
• Observe and record the species present in a habitat
• Samples should be taken
• Visual surveys should be taken, to ensure that nothing is missed
• However, this does not take into account the number of individuals of each species
• Not sufficient data to measure diversity alone
SPECIES EVENNESS
• Is the number of individuals of each species
• Relative to population size
• Relative abundance of each species
• A habitat with even numbers of species is likely to be more diverse than one with a dominant species
• A quantitative survey is carried out to asses this:
SURVEY FREQUENCY OF PLANTS
• Count number of each species present in sample area
• With smaller plants is easier to calculate percentage cover
DENSITY OF ANIMALS
• Careful observation can be made, counting individuals
• Animals can be captured, marked then released
• This will give an idea of the population size
• Counting percentage cover
SIMPSON’S INDEX OF BIODIVERSITY
• Diversity index is a better way of describing biodiversity
• It takes into account both species richness and evenness
• Gives an idea of the number of each species relative to population size
• Small and large populations are treated differently
• Simpson’s index measure the diversity of a habitat
The formula is: D =1 – [nN]2
Where n = the number of individuals of a certain species And N = the total number of individuals of all species
GENETIC DIVERSITY
Genetic diversity refers to the number of different variations of alleles at a particular locus there is in a species or population. For example, rare and endangered species have a limited genetic diversity because there are only a few of them: their gene pool is small
CONSERVATION
Conservation of endangered species outside of their natural environment. All of these techniques carry the risk of disturbance to the natural environment
NATURAL SELECTION
• Genetic and phenotypic diversity exists in a population
• Some variation arises from mutation which creates a new allele for a gene
• Some new alleles equip the individual with an advantage
o Easier to survive
o E.g. can run faster or survive longer without water
• This individual is more likely to survive and reproduce
• The allele is passed down to its offspring
• Its offspring also have the survival advantage
• Organisms carrying this allele continue to survive and reproduce
• The allele is passed down generations
• The allele frequency increases within the population
• Population is better adapted to its environment
o Adaptations can be physiological, behavioural, or anatomical