3.1 An introduction to biodiversity

Significant ideas:

  • Biodiversity can be identified in a variety of forms, including species diversity, habitat diversity and genetic diversity.
  • The ability to both understand and quantify biodiversity is important to conservation efforts.

Knowledge and understanding:

  1. Biodiversity is a broad concept encompassing the total diversity of living systems, which includes the diversity of species, habitat diversity and genetic diversity.
  2. Species diversity in communities is a product of two variables: the number of species (richness) and their relative proportions (evenness).
  3. Communities can be described and compared through the use of diversity indices. When comparing communities that are similar, low diversity could be indicative of pollution, eutrophication or recent colonization of a site. The number of species present in an area is often indicative of general patterns of biodiversity.
  4. Habitat diversity refers to the range of different habitats in an ecosystem or biome.
  5. Genetic diversity refers to the range of genetic material present in a population of a species.
  6. Quantification of biodiversity is important to conservation efforts so that areas of high biodiversity may be identified, explored, and appropriate conservation put in place where possible.
  7. The ability to assess changes to biodiversity in a given community over time is important in assessing the impact of human activity in the community.

Applications and skills:

  • Distinguish between biodiversity, diversity of species, habitat diversity and genetic diversity.
  • Comment on the relative values of biodiversity data.
  • Discuss the usefulness of providing numerical values of species diversity to understanding the nature of biological communities and the conservation of biodiversity.


  • International scientific collaboration is important in the conservation of biodiverse regions.

Theory of knowledge:

  • The term “biodiversity” has replaced the term “nature” in much literature on conservation issues—does this represent a paradigm shift?
  • Diversity index is not a measure in the true sense of a word, but merely a number (index), as it involves a subjective judgment on the combination of two measures: proportion and richness. Are there examples in other areas of knowledge of the subjective use of numbers?


  • Foundations of ESS (topic 1)
  • Investigating ecosystems (2.5)
  • Water pollution (4.4)
  • Acid deposition (6.4)
  • Climate change — causes and impacts (7.2)