Investigating biodiversity

Habitat diversity- the number of different habitats in an area 

Species diversity- diversity of different number of species and abundance of each species in an area.

Genetic diversity- variationof alleles within a speacies or population of species

collecting data- finding out the numebr of different species or number of individual species. a sample is taken and estimates on the whole habitat is based on the sample. 

Random sampling- makes sure the smaple isnt biased in this each iste has to have the same probablity of being chosen.

Non random sampling- used when you need to make sure all differnet areas are sampled 

systematic- samples are taken at fixed intervals along a line

Opportunistic- when samples are chosen by investigator

Stratified- when different areas are indentified and sampled separtately in proportion to thier whole habitat.

estimating biodiversity using samples

1) Choose site to sample

2 use appropriate equipment to record the number of different species or individuals (quadrat, insect trap, sweepnet, net)

3) repeat process, samples should be chosen the same way as the first sample

4) number indivuals in a whole habitat can be estimated by calculating the mean and multiplying it by size of whole habitat

5) compare to other habitats, but must use same technique

species richness- number of different species in an area

species evenness- measure of relevant abundance of each species in an area

Simpson's index of biodiversity (D)

used to measure species diversity

D=1-(E(n/N)^2)  where E=sum of   n=total number of orangisms in one species N=total number of all organisms

always a value between 0-1 

Genetic diversity

important as a species with high genetic diversity are more likely to adapt to a change in environment

Polymorphism- locus that has 2 or more alleles

assessing genetic diversity

working out the proportion of polymorphic gene loci

proportionof polymorphic gene loci= number of polymorphic gene loci/ total number of loci

factors affecting biodiversity

Human population growth

1) habitat loss- we develop more land for housing and food, destroying habitats

 2) Over- exploitation- greater demand for resources means alot of resources are used made faster than they can replenished, destroys habitats and affects species directly

 3) urbanisation- city and road development can isolate species meaning populations are unable to interbreed and gentic diversity is decreased

 4) pollution- produce more and more waste and pollution which can kill species and destroy habitats


 1) habitat loss- land is cleared for large fields reducing habitat diversity

 2) loss of local plants and animals- local and naturally occuring organisms are seen as weeds and so are destroyed reducing species diversity

 3) loss of heritage varieties- traditional species are lost becaus ethey dont make enough money which reduces species diversity

climate change- significant long term change in an areas climate


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