How to Preserve Biodiversity (DP IB Biology)

Conserving Biodiversity

• As human activities continue to cause a decline in biodiversity, the need for solutions to this problem increases

• The problem is complex, and there is no one simple solution, so a mixture of different approaches is needed

  • The complexities are often due to conflicts between the needs of the natural world and the needs of humans; these conflicts are not always easy to resolve

• Examples of different approaches to dealing with the biodiversity crisis include

  • In situ conservation, e.g.

    • Protected areas

    • Rewilding

    • Reclamation

  • Ex situ conservation, e.g.

    • Zoos

    • Botanic gardens

    • Seed banks

    • Tissue banks

In situ conservation

Protected areas

• A protected area is a defined geographical space, such as a national park or nature reserve, that is managed and protected for the purposes of conservation

• National parks are government-controlled areas within countries where the wildlife and environment are protected

• Nature reserves are smaller regions than national parks, and can be on privately or publicly owned land

• Restrictions inside protected areas could include

  • Humans access is strictly controlled

  • Industrial activities such as agriculture and building are tightly regulated

  • Hunting is limited or completely prohibited

CC BY-SA 3.0 , via Wikimedia Commons

Kruger National park is the largest national park in South Africa

Rewilding

• This is the restoration of ecosystems to a point at which they can sustain themselves; such sustainable ecosystems are by their nature biodiverse habitats

• Rewilding can be allowed to occur on private or publicly owned land

• Rewilding can be active or passive

  • Active rewilding involves human intervention, e.g. removing human features such as roads, and reintroducing locally extinct species

  • Passive means leaving an area alone to allow ecological processes to gradually restore themselves, e.g. stopping the management of land to allow natural succession to occur

    • Note that passive rewilding will not work for the restoration of some habitat types, e.g. grassland habitats often require grazing to prevent the dominance of tree species

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Longhorn cattle at the Knepp estate in the UK mimic the action of extinct ancient grazing species, creating a diverse grassland habitat

Reclamation

• Reclamation refers to the reclaiming and restoration of areas that have been damaged by human activities, e.g. abandoned quarries or areas where deforestation has taken place

• Such projects aim to restore previously existing ecosystems

Ex situ conservation

Zoos

• Captive breeding programmes in zoos can increase the number of individuals of a species

  • This can be carried out by artificial insemination, allowing the flow of genes between individuals that may be living in different zoos

    • This prevents problems that can arise from low genetic diversity

    • This can avoid difficulties with captive breeding

  • Captive breeding can lead to the release of individuals back into the wild

• Zoos are an invaluable resource for scientific research

  • Scientists are able to closely study animal genetics, behaviours and habitat requirements

Botanic gardens

• Botanic gardens are the plant equivalent of zoos

• They use cuttings and seeds collected from the wild to establish a population of the endangered species in captivity

  • Methods of tissue culturing and cloning can also be used to obtain large numbers of plants from a small sample size

• The captive population can be used in the future for reintroduction into habitats where they have become rare

• Research is a major role of botanic gardens

  • Scientists can investigate reproduction and growth in different plant species so that they can be grown in captivity

  • Habitat requirements can be assessed so that new habitats can be found if necessary

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Botanic gardens, such as this one in Rio de Janeiro, Brazil, can increase the populations of threatened plant species and carry out scientific research and education

Seed banks

• A seed bank is a facility that conserves plant diversity by drying and storing seeds in a temperature-controlled environment

  • Cool, dry conditions generally increase the length of time for which seeds remain viable

  • Seeds can only be stored for so long; after a certain period of time the stored seeds are grown into plants and fresh seeds for storage are taken from those plants

• If the plant species goes extinct then the seeds can be used to grow them again

• Usually, seeds of the same species are collected from different sites to maintain genetic diversity

• The Svalbard Global Seed Vault in Norway contains seeds from almost 1 million plant species
  

  • It is located in the Arctic Circle with ideal environmental conditions

  • Many organisations send seeds from crop plants to be stored there for safekeeping

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The Svalbard Global Seed Vault in Norway contains seeds from almost 1 million plant species

Tissue banks

• Tissue banks, or frozen zoos, store genetic material from animals at very low temperatures

  • It is thought that properly frozen tissue samples can last indefinitely

• Ideally, samples are collected from different individuals of the same species to maintain genetic diversity

• Two different types of tissue can be stored in tissue banks

  • Germplasm

    • This includes reproductive tissue, such as sperm cells, egg cells, and embryos

    • This material can be used by zoos in captive breeding programmes

    • In theory, IVF could be carried out with a suitable surrogate species to bring back an extinct species from this tissue

  • Somatic tissue

    • This is non-reproductive tissue, or body cells

    • This type of tissue contains the full genome of the species, and can be used for DNA research

    • It is thought that such tissue could be used for cloning extinct species in the future

Conserving Biodiversity: Selecting Species

Prioritising species for conservation

• There are so many species that need protection that it can seem like an impossible task to decide where to allocate the limited resources available

• The Evolutionarily Distinct and Globally Endangered (EDGE) programme works together with the Zoological Society of London (ZSL), to carry out research and to highlight the needs of certain species

• Priority is decided on the basis of a species being

  • Evolutionarily distinct

    • Species have few close evolutionary relatives

    • Species are unusual in appearance, behaviour, and DNA

    • Species represent a part of Earth's evolutionary tree that is not represented anywhere else

  • Globally endangered

    • The IUCN red list is used to provide information about the threat level of an evolutionarily distinct species

    • A species must be globally threatened, not just threatened on a local level

• A species must be both evolutionarily distinct and globally endangered to be prioritised by the EDGE programme

  • Examples of priority EDGE species include

    • Largetooth sawfish

    • Chinese giant salamander

    • Purple frog

• The EDGE of existence programme highlights the needs of EDGE species to local, government, and international conservation organisations to ensure that such species are not lost before their plight is even recognised

CC BY-SA 4.0, via Wikimedia Commons

The Chinese giant salamander is both evolutionarily distinct and globally endangered, and is a focal species for the EDGE programme

NOS: Issues such as which species should be prioritised for conservation efforts are complex and need to be debated

• The considerations of the EDGE programme are important, but there are complex ethical, environmental, political, social, cultural and economic issues when it comes to making decisions about priority species for conservation, e.g.

  • Some species may not be at a very high threat level globally, but they may be important for the maintenance of an ecosystem that supports other, more threatened species

  • A species may be culturally important for a particular nation

  • There may be political reasons why conserving particular habitats is very difficult, e.g. being located in a warzone

• For this reason, EDGE do not make decisions about conservation, but they can pass on important information to stakeholders, allowing a range of people to be involved with the debate