18.3 Conservation

Extinction is the end of a species. Environmental change and human activity can reduce survival and reproduction until a population becomes unable to persist; several pressures may act together.

• Climate or environmental change — changed temperature, sea level, ocean conditions or ice cover can make a habitat unsuitable and reduce access to food.
• Competition — limited food, water, habitat or mates can reduce population size; competition may be within or between species.
• Hunting and overexploitation — removing too many individuals, especially from a vulnerable population, can leave too few to survive.
• Habitat degradation or loss — destruction, pollution or reduction of the habitat removes the resources and conditions on which the species depends.
• Introduced invasive species — a non-native species may lack natural predators, competitors or pathogens, increase rapidly, and then reduce native populations through competition or disease.

Use the causal chain: direct pressure → reduced resources, survival or reproduction → smaller population → increased extinction risk. Habitat loss can also force individuals into the remaining area, increasing competition. A small population may then experience more inbreeding and genetic drift, reducing genetic variation and fitness; this feedback can increase mortality and reduce reproduction further.

Do not treat one pressure as necessary in every extinction event, or confuse a falling population with immediate extinction. This card explains causes and the small-population vulnerability feedback; conservation methods, IUCN status and assisted reproduction are separate cards.

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.

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.

Endangered mammals may have small, isolated populations, inbreeding and too few suitable reproductive mates. Assisted reproduction can move gametes or embryos between animals and give reproduction more controlled support.

1. Obtain eggs and sperm from suitable individuals while protecting the reproductive female; the source animals retain the species’ genetic identity.
2. In IVF, extract eggs, keep them briefly in culture, mix them with semen outside the body, and allow zygotes to develop into embryos.
3. Transfer an embryo to the mother or a suitable surrogate; embryo transfer can reduce pregnancy risk for a vulnerable female.
4. In surrogacy, a female carries an embryo to full term after her uterus has been prepared; artificial insemination or IVF can be used to create the embryo.
5. Offspring may be managed in captivity and, if the habitat and population conditions are suitable, used in a later reintroduction programme.

IVF confirms fertilisation outside the body. Embryo transfer moves an embryo after fertilisation, and surrogacy focuses on the female that carries it; a surrogate may be the same or a closely related species when compatibility permits.

Assisted reproduction can increase reproductive opportunities, but it does not by itself restore habitat, remove inbreeding risk or guarantee adaptation after release. Cost, welfare, genetic diversity, suitable habitat and reintroduction success remain constraints. General conservation settings, invasive-species control and IUCN/CITES roles are separate cards.

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.

1. Identify the introduced species, the route by which it arrived and the native species or ecosystem processes affected.
2. Monitor its spread and population increase, together with competition, predation, disease and changes in biodiversity or productivity.
3. 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.
4. 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.
5. 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.

The IUCN assesses the conservation status of animal and plant species worldwide. Its classification uses evidence about population numbers, threats and risks to those populations; scientists use data and modelling to estimate the appropriate category, which is made public through the IUCN Red List.

Use the assessment chain:

1. Gather evidence about population size or trend, distribution, threats and risks, noting whether the evidence is sufficient.
2. Use the available data and modelling to assess the species against the IUCN classification system.
3. Record the resulting conservation-status category and communicate it through the public Red List.
4. Use the status assessment to identify species needing conservation attention and to support coordinated decisions about safeguarding them.
5. Continue collecting evidence and update the assessment as populations, threats or data quality change.

More severe population decline, stronger threats or greater risk can support a more urgent conservation-status assessment. A status category is therefore an evidence summary used to guide priorities; it is not itself a recovery programme or a guarantee that a species will be protected.

Do not invent a numerical threshold or treat one observation as a complete assessment. The SME page explicitly allows insufficient-data outcomes and states that scientists continually review and update species status, so scale, evidence quality and uncertainty matter. IUCN status assessment is distinct from CITES trade controls and from the habitat, invasive-species and assisted-reproduction methods in neighbouring cards.