Biodiversity

The term biodiversity refers to the variety of life on earth at all its levels, from genus to ecosystems.

The importance of biodiversity

  • essential for maintaining a balanced ecosystem for all organisms

  • all species are interconnected - dependence

  • biodiversity cycles

Measuring biodiversity

  • allows environmental change to be measured

  • identifies species present

  • see effect of climate change, human action etc

Habitat biodiversity

  • refers to the number of different habitats found within an area

  • each habitat can support a number of different species

  • generally the greater the habitat biodiversity the greater the species biodiversity will be within that area

Species biodiversity

  • Species richness - the number of different species living in a particular area

  • species evenness - a comparison of the numbers of individuals of each species living in a community

  • Simpson’s index of diversity

  • Simpson's index

    • N = total number of organisms of all species

    • n = total number of organisms of a particular species

    • D = diversity index: the probability that two randomly selected individuals will belong to the same species/group

    • Highest possible value is 1

    • large value = greater diversity

Genetic biodiversity

  • refers to variety of genes that make up a species

  • greater genetic biodiversity within a species

    • allows for better adaptation to a changing environment

    • more likely to result in individuals who are resistant to disease

Factors affecting biodiversity

  • Mutation - formation of new alleles leads to variation

    • increase

  • gene flow - immigration and emigration result in movement of alleles between population

    • increase

  • selective breeding - decreasing frequency of alleles resulting in fewer characteristics

    • decrease

  • artificial cloning

    • decrease

  • natural selection

    • decrease

  • Genetic drift - change in allele frequency due to random nature/chance in a small population

    • decrease

  • genetic bottleneck - large numbers of a population die off

    • decrease

  • founder effect - few individuals of a species colonise a new area

    • decrease

Polymorphic and monomorphic genes

  • More than one allele for a gene is polymorphic

    • the gene that controls antigens on red blood cells (A, B, O)

    • polymorphic gene example

  • Only one version of a gene in a population is monomorphic

    • the gene that produces amylase

    • monomorphic gene example

DNA electrophoresis

DNA electrophoresis

Calculating genetic biodiversity

  • more polymorphic loci means a higher genetic biodiversity

  • Statistical genetic biodiversity equation