SL Content Statements

• A4.2.1

  Biodiversity as the variety of life in all its forms, levels and combinations

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  Include ecosystem diversity, species diversity and genetic diversity.
  

• A4.2.2

  Comparisons between current number of species on Earth and past levels of biodiversity

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  Millions of species have been discovered, named and described but there are many more species to be discovered. Evidence from fossils suggests that there are currently more species alive on Earth today than at any time in the past.
  NOS: Classification is an example of pattern recognition but the same observations can be classified in different ways. For example, “splitters” recognize more species than “lumpers” in a taxonomic group.
  

• A4.2.3

  Causes of anthropogenic species extinction

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  This should be a study of the causes of the current sixth mass extinction, rather than of non-anthropogenic causes of previous mass extinctions. To give a range of causes, carry out three or more brief case studies of species extinction: North Island giant moas (Dinornis novaezealandiae) as an example of the loss of terrestrial megafauna, Caribbean monk seals (Neomonachus tropicalis) as an example of the loss of a marine species, and one other species that has gone extinct from an area that is familiar to students.

• A4.2.4

  Causes of ecosystem loss

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  Students should study only causes that are directly or indirectly anthropogenic. Include two case studies of ecosystem loss. One should be the loss of mixed dipterocarp forest in Southeast Asia, and the other should, if possible, be of a lost ecosystem from an area that is familiar to students.

• A4.2.5

  Evidence for a biodiversity crisis

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  Evidence can be drawn from Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services reports and other sources. Results from reliable surveys of biodiversity in a wide range of habitats around the world are required. Students should understand that surveys need to be repeated to provide evidence of change in species richness and evenness. Note that there are opportunities for contributions from both expert scientists and citizen scientists.
  NOS: To be verifiable, evidence usually has to come from a published source, which has been peer- reviewed and allows methodology to be checked. Data recorded by citizens rather than scientists brings not only benefits but also unique methodological concerns.
  

• A4.2.6

  Causes of the current biodiversity crisis
  

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  Include human population growth as an overarching cause, together with these specific causes: hunting and other forms of over-exploitation; urbanization; deforestation and clearance of land for agriculture with consequent loss of natural habitat; pollution and spread of pests, diseases and invasive alien species due to global transport.
  

• A4.2.7

  Need for several approaches to conservation of biodiversity

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  No single approach by itself is sufficient, and different species require different measures. Include in situ conservation of species in natural habitats, management of nature reserves, rewilding and reclamation of degraded ecosystems, ex situ conservation in zoos and botanic gardens and storage of germ plasm in seed or tissue banks.
  

• A4.2.8

  Selection of evolutionarily distinct and globally endangered species for conservation prioritization in the EDGE of Existence programme

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  Students should understand the rationale behind focusing conservation efforts on evolutionarily distinct and globally endangered species (EDGE).
  NOS: Issues such as which species should be prioritized for conservation efforts have complex ethical, environmental, political, social, cultural and economic implications and therefore need to be debated.