Conservation

2026 Syllabus Objectives

By the end of this topic, you should be able to:

  1. Explain why populations and species can become extinct as a result of: climate change, competition, hunting by humans, degradation and loss of habitats

  2. Outline reasons for the need to maintain biodiversity

  3. Outline the roles of zoos, botanic gardens, conserved areas (including national parks and marine parks), 'frozen zoos' and seed banks, in the conservation of endangered species

  4. Describe methods of assisted reproduction used in the conservation of endangered mammals, limited to IVF, embryo transfer and surrogacy

  5. Explain reasons for controlling invasive alien species

  6. Outline the role in conservation of the International Union for Conservation of Nature (IUCN) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

1. Why Populations and Species Become Extinct

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Extinction means that a species has completely disappeared - there are no organisms of that species left anywhere, either in the wild or in captivity. Several factors can push populations toward extinction.

Climate Change

Changes in climate can make it impossible for species to survive in their normal habitats. For example:

  • Global warming causes temperatures to rise. This particularly affects species adapted to cold environments.
  • Rising ocean temperatures damage marine ecosystems. Coral reefs are especially vulnerable - when water gets too warm, the algae living inside coral polyps leave, causing the coral to turn white (called coral bleaching) and eventually die.
  • Natural disasters linked to climate change can destroy habitats rapidly.
  • Species may not be able to adapt quickly enough to changing conditions like temperature, rainfall patterns, or seasonal changes.

Competition

Competition occurs when different species need the same resources (food, water, shelter, breeding sites). Species can become extinct when:

  • A competitor species is better adapted to the environment and wins the competition for resources.
  • The competing species reproduces faster or uses resources more efficiently.
  • The species cannot find enough food or space because competitors have taken these resources.

Hunting by Humans

Human hunting activities have driven many species close to extinction or completely wiped them out:

  • Poaching means illegal hunting of animals, often for valuable body parts. For example, African elephants are killed for their ivory tusks, which can be sold for high prices.
  • Overfishing removes fish from oceans faster than they can reproduce, reducing populations dramatically.
  • Hunting for meat, skins, or other products can reduce populations to dangerously low levels.
  • Some animals are killed because humans see them as pests or threats to crops and livestock.

Degradation and Loss of Habitats

This is one of the most important causes of extinction today. Habitat loss means the places where organisms live are destroyed or damaged. Habitat degradation means the habitat becomes lower quality and cannot support as many organisms.

Human activities causing habitat loss include:

  • Deforestation - cutting down forests for timber or to clear land for farming, housing, or roads.
  • Reclamation of land - draining wetlands or filling in coastal areas to create land for human use.
  • Pollution damaging habitats (see below).
  • Urbanization - building cities and towns destroys natural habitats.

When habitats are lost:

  • Organisms have nowhere to live, feed, or breed.
  • Populations become fragmented (split into small, isolated groups) which makes breeding difficult.
  • Food chains and food webs are disrupted.

Pollution also contributes to habitat degradation:

  • Air pollution: Carbon dioxide (CO₂) and oxides of nitrogen and sulfur cause acid rain and contribute to global warming. Acid rain damages forests and makes lakes and rivers too acidic for organisms to survive.
  • Industrial and domestic pollution: Chemicals like PCBs (polychlorinated biphenyls) harm wildlife by reducing fertility and weakening immune systems in birds and mammals.
  • Marine pollution: Plastic waste in oceans is often mistaken for food. For example, turtles eat plastic bags thinking they are jellyfish, which blocks their digestive systems and kills them.

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