Biodiversity and Classification

Biodiversity encompasses the variety of life at all levels — from genetic diversity within species, to species diversity within habitats, to ecosystem diversity across landscapes. Classification provides a systematic framework for organising and understanding this diversity. This topic is central to A-Level Biology, connecting ecology, evolution, and conservation in a way that underpins much of the specification.

Key Definition: Biodiversity is the variety of living organisms in an area, encompassing genetic diversity, species diversity, and ecosystem diversity.

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What Is Biodiversity?

Biodiversity can be considered at three levels:

Level	Description	Example
Genetic diversity	Variation in alleles within a species	Different alleles for coat colour in mice; different haemoglobin alleles in humans
Species diversity	Number and abundance of different species in a community	Tropical rainforests have high species diversity; a monoculture field has low species diversity
Ecosystem diversity	Range of different habitats and communities in an area	A region containing woodland, wetland, heathland, and grassland