#145 Biodiversity

Biodiversity is much more than a list of all the species in a particular area.










species: a group of organisms with

• similar morphological, physiological, biochemical and behavioural features
• can interbreed to produce fertile offspring
• reproductively isolated from other species

ecosystem: a relatively self-contained, interacting community of organisms, and the environment in which they live in and with which they interact

niche: role of an organism in an ecosystem

habitat: where a species lives within an ecosystem

Biodiversity: degree of variation of life forms in an ecosystem:

• variation in ecosystems or habitats
• number of species and their relative abundance
• genetic variation within each species

Species diversity

- species richness: number of species in a community

- species diversity: species richness and a measure of the eveness of abundance of different species

Ecosystems with high species diversity tend to be more stable --> more able to resist changes

- some ecosystems are dominated

- the tropics are important centres for diversity

Genetic diversity

genetic diversity: diversity of alleles within the genes in the genome of a single species; calculated 

• what proportion of genes have different alleles
• how many alleles there are per gene

There is genetic diversity:

• between populations
• within each population

Syllabus 2016-2018 18.1 Biodiversity Biodiversity is much more than a list of all the species in a particular area. a) define the terms species, ecosystem and niche  b) explain that biodiversity is considered at three different levels:  • variation in ecosystems or habitats  • the number of species and their relative abundance  • genetic variation within each species  c) explain the importance of random sampling in determining the biodiversity of an area  d) use suitable methods, such as frame quadrats, line transects, belt transects and mark-release-recapture, to assess the distribution and abundance of organisms in a local area  e) use Spearman’s rank correlation and Pearson’s linear correlation to analyse the relationships between the distribution and abundance of species and abiotic or biotic factors  f) use Simpson’s Index of Diversity (D) to calculate the biodiversity of a habitat and state the significance of different values of D