Measuring and maintaining biodiversity – AQA A Level Biology Summary Notes
Biodiversity means the variety of life. Relates to a range of habitats from small local habitat to the
Earth
Species diversity
- Number of species and number of individuals of each species within any one community
Genetic diversity
- Number of different alleles of each gene possessed by the individuals that make up a
population of species
Ecosystem diversity
- Range of different habitats, from a small local habitat to the whole of the earth
Species richness is a measure of the number of different species in a community at a given time
- HOWEVER, species richness is NOT A FULL MEASURE of species diversity
- BECAUSE only considers number of different species in given community but not the number
of individuals of each of these species
Species abundance
- Number of individuals of each species in a community
Index of diversity describes the relationship between the number of species in a community and
number of individuals in each species
Index of diversity = better measure of species diversity
- Considers number of species in a community AND number of individuals of each species (ie
population sizes)
- Takes into account that there may be many of some species and few of others
Communities associated with large indexes of diversity typically have many NICHES, allowing
organisms from different species to survive with less interspecific competition = MORE STABLE
Index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
Biodiversity means the variety of life. Relates to a range of habitats from small local habitat to the
Earth
Species diversity
- Number of species and number of individuals of each species within any one community
Genetic diversity
- Number of different alleles of each gene possessed by the individuals that make up a
population of species
Ecosystem diversity
- Range of different habitats, from a small local habitat to the whole of the earth
Species richness is a measure of the number of different species in a community at a given time
- HOWEVER, species richness is NOT A FULL MEASURE of species diversity
- BECAUSE only considers number of different species in given community but not the number
of individuals of each of these species
Species abundance
- Number of individuals of each species in a community
Index of diversity describes the relationship between the number of species in a community and
number of individuals in each species
Index of diversity = better measure of species diversity
- Considers number of species in a community AND number of individuals of each species (ie
population sizes)
- Takes into account that there may be many of some species and few of others
Communities associated with large indexes of diversity typically have many NICHES, allowing
organisms from different species to survive with less interspecific competition = MORE STABLE
Index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
