Defining biodiversity

Biodiversity refers to the variety of organisms in an area.

Levels of biodiversity:

• Ecosystem diversity (habitat diversity) - The number of habitats.
• Species diversity - The number of species and the number of individuals in each species.
• Genetic diversity - The variation in alleles within a population of a species.

High genetic biodiversity allows for better adaptation to a changing environment and resistance to disease.

Key terms related to biodiversity:

• Habitat - The place where a species lives within an ecosystem.
• Community - The living organisms of all species found in a particular ecosystem at a particular time.
• Ecosystem - A relatively self-contained, interacting community of organisms and their environment.

Interspecific and intraspecific variation

Variation refers to differences between individuals. Generally, variation is due to a combination of genetic and environmental influences.

Interspecific variation:

• This is variation between different species.
• It is due to different genes causing differences in physical traits, adaptations, habitats, etc. and environmental factors like climate, diet, lifestyle, etc.

Intraspecific variation:

• This is variation between individuals within a species.
• It is due to different alleles (gene variants) and environmental factors.

Species richness and species evenness

Species richness and species evenness are measures of biodiversity.

Species richness:

• The total number of different species in a habitat.
• It is quantified by taking random samples and counting the species present.
• A higher species richness indicates greater diversity.

Species evenness:

• A comparison of the numbers of individuals of each species in a community.
• It is measured by taking samples and counting individuals of each species.
• More even abundances mean higher species evenness and diversity.