18.3 Conservation
- Syllabus
- 9700–2028–2029
- Topic
- 18.3
- Level
- A2
Learning objectives
18.3.1Extinction causes• Extinction causes:- Climate change- Competition- Hunting by humans- Habitat degradation and loss18.3.2Reasons to maintain biodiversity• Reasons to maintain biodiversity18.3.3Ex situ and protected-area conservation• Conservation roles: zoos, botanic gardens, conserved areas (national/marine parks), 'frozen zoos', seed banks18.3.4Assisted reproduction in endangered mammals• Assisted reproduction in endangered mammals: IVF, embryo transfer, surrogacy18.3.5Invasive alien species• Reasons for controlling invasive alien species18.3.6Conservation organisations• Conservation organisations: IUCN, CITES
Four pressures can drive populations to extinction
A species becomes extinct when no living individuals remain. Extinction risk rises when a pressure repeatedly lowers survival or reproductive success so that deaths exceed births and the population can no longer recover.
| Pressure | Route to extinction |
|---|---|
| Climate change | temperature, rainfall, sea level or ocean conditions shift beyond tolerance; habitat, food or breeding conditions are lost |
| Competition | another population uses the same limited food, space, light, water or mates more successfully, reducing survival or reproduction |
| Hunting by humans | individuals are removed faster than reproduction replaces them, especially when breeding adults are taken |
| Habitat degradation or loss | pollution, fragmentation or destruction reduces usable area, resources, shelter and access to mates |
Pressures can reinforce one another. Habitat loss may crowd organisms into smaller areas and increase competition. As a population shrinks, loss of genetic variation and inbreeding can reduce its ability to respond to further change, increasing the chance that the decline continues.
A fall in abundance is not yet extinction, and one pressure need not act alone. Explain the complete chain from the named pressure to reduced survival or reproduction, population decline and eventual loss of the species.
Biodiversity has ecological and human value
Maintaining biodiversity protects ecological relationships and preserves options for people and other species. The reasons overlap: ecosystems, species and genes support one another, so loss at one level can reduce benefits at others.
- Ecological stability and resilience — more diverse ecosystems may contain species able to tolerate environmental change, while loss of a keystone species can disrupt many other organisms.
- Environmental services — plants, fungi, bacteria and other organisms contribute to carbon dioxide absorption, the water cycle, decomposition, nutrient cycling and food webs.
- Genetic resources and future value — wild relatives can provide alleles that help crops resist disease or other disasters, and organisms may contain medicines or useful materials that have not yet been discovered.
- Economic value — biodiversity supports medicines, ecotourism, employment, science and technology.
- Social, cultural and aesthetic value — natural environments provide recreation, inspiration and opportunities for people to connect and learn.
- Moral and ethical value — people may regard humans as responsible for reducing human-caused loss and valuing other species.
These reasons are interdependent rather than isolated: genetic and species diversity can support ecosystem resilience; functioning ecosystems provide services and resources; and those benefits affect human wellbeing and future choices. The evidence supports a general reason to maintain biodiversity, not a guarantee that every diverse ecosystem resists every disturbance.
Do not reduce conservation value to economic usefulness alone, and do not assume that an ecosystem service or future genetic resource is certain or unlimited. This card explains why biodiversity matters; conservation methods, assisted reproduction, invasive-species control and IUCN/CITES tools are separate cards.
Conservation can be in situ or ex situ
In situ conservation protects a species in its natural habitat. Ex situ conservation protects organisms or their genetic material outside the original habitat when in situ protection is not sufficient or possible.
- Protected areas (in situ) — national and marine parks protect habitats and species through controls on access, development, hunting, overfishing or pollution; the natural support systems remain available.
- Zoos and botanic gardens (ex situ) — captive populations support conservation, research and education, and may provide material for future reintroduction; suitable conditions and genetic diversity must be maintained.
- Frozen zoos and gene banks (ex situ) — animal eggs, sperm or tissues can be stored at very low temperature to preserve genetic material from different individuals.
- Seed banks (ex situ) — dried seeds are stored under controlled conditions to conserve plant genetic diversity and allow future regrowth; some plants require continued growth or tissue culture instead of freezing.
Choose the method to match the threat and biological need. In situ protection maintains the whole habitat but depends on effective management and community acceptance. Ex situ storage or captivity can protect a small or isolated population, but it costs resources, may not reproduce the natural habitat, and small captive populations can lose genetic diversity. Long-term success also depends on a suitable habitat or use for the conserved material.
In situ and ex situ methods are complementary, not interchangeable. This card compares conservation settings and genetic-resource storage; assisted-reproduction procedures, invasive-species control and IUCN/CITES roles are separate cards.
IVF creates embryos; transfer and surrogacy support gestation
Assisted reproduction can produce offspring when endangered mammals have few suitable mates or reproduce poorly in captivity. Genetic records guide the choice of parents so that breeding can maintain variation and limit inbreeding.
| Method | What happens | Conservation role |
|---|---|---|
| IVF | hormones stimulate egg maturation; eggs are collected, mixed with sperm outside the body, and fertilised embryos are cultured briefly | gametes from genetically suitable animals can be combined without natural mating |
| Embryo transfer | an early embryo is placed into the uterus of a prepared recipient female | a donor's embryo can complete development in another female, allowing valuable genes to produce more offspring |
| Surrogacy | the recipient female carries the transferred embryo through pregnancy and gives birth | a surrogate can carry an embryo when the genetic mother should not or cannot undergo pregnancy |
In a typical IVF programme: stimulate egg maturation → collect eggs and sperm → fertilise outside the body → check early embryos → transfer a selected embryo to a recipient uterus → monitor pregnancy and birth. The offspring's nuclear genes come from the egg and sperm donors, not from the surrogate.
The three terms describe linked but different stages: IVF creates the embryo, embryo transfer moves it, and surrogacy is gestation by a recipient. These methods do not restore habitat or automatically solve low genetic diversity, cost, welfare or post-release survival.
Control invasive alien species through prevention and evidence
An invasive species is a species that has moved into an ecosystem where it was previously unknown and then disrupts the balance of the ecosystem. Most recorded introductions are linked to human transport, trade or deliberate release.
- Identify the introduced species, the route by which it arrived and the native species or ecosystem processes affected.
- Monitor its spread and population increase, together with competition, predation, disease and changes in biodiversity or productivity.
- Prevent further introduction or spread by controlling the human pathways that transport species between ecosystems; deliberate biological-control introductions also require evidence because a non-native species may become invasive.
- If control is considered, judge the intervention against reduction of the invasive population and recovery of native species, while checking non-target effects, ecosystem disruption, cost and ethical acceptability.
- Continue long-term monitoring: a short-term fall in numbers is not the same as lasting recovery of the native community.
The risk chain is: few natural predators, competitors or pathogens → rapid population increase → competition for prey, nutrients, light or space, successful predation or introduction of disease → native-population decline and reduced biodiversity/productivity. Human health, travel and economic costs can also be affected.
Do not call every non-native species invasive, and do not assume that one control action is automatically effective or harmless. The matched SME page does not specify a physical, chemical or biological control protocol, so no named treatment, dose or non-target claim is added here. Assisted reproduction and IUCN/CITES roles are separate cards.
IUCN assesses risk; CITES regulates international trade
IUCN and CITES support conservation with different tools. IUCN provides evidence-based assessments of extinction risk; CITES is an international agreement that controls trade in listed wild animals, plants and their products.
| Organisation | Main role | How this helps conservation |
|---|---|---|
| IUCN | assesses population size and trend, distribution, threats and extinction risk; publishes conservation-status categories in the Red List | identifies and prioritises species at risk, informs governments and conservation organisations, raises awareness and supports planning; assessments are updated as evidence changes |
| CITES | lists species in appendices and regulates or prohibits their international commercial trade; permitted trade requires documentation and monitoring | reduces unsustainable legal trade and illegal international trade, gives countries a shared framework, and makes cross-border enforcement and trade records possible |
The tools can complement each other: an IUCN assessment may show that trade contributes to risk, while CITES controls the international trade route. A species can still receive CITES protection even when IUCN data are insufficient, because the organisations use different processes.
An IUCN Red List category is not itself a law or trade ban. CITES regulates international trade; it does not assign Red List categories or directly remove every threat such as habitat loss, climate change or domestic exploitation.