Ex-situ Conservation

Ex-situ conservation is the strategy of protecting a threatened species outside its natural habitat, in a controlled setting specifically established and managed for that purpose. It is generally regarded as a complementary strategy to in-situ conservation rather than a replacement for it, used particularly for species whose wild population and natural habitat have already been reduced to the point where in-situ protection alone can no longer be relied upon to guarantee the species' survival, or where breeding a reliable captive population is itself considered an important safeguard against the risk of a wild population being lost entirely.

Zoological parks (zoos) and botanical gardens are among the oldest and most familiar forms of ex-situ conservation, maintaining living populations of animal and plant species respectively under carefully managed, artificial conditions. Modern zoos increasingly operate coordinated captive-breeding programmes for threatened species, sometimes across multiple institutions in different countries, with the explicit long-term goal of eventually reintroducing captive-bred individuals back into a suitable, protected wild habitat once conditions allow. Wildlife safari parks offer a related model, housing animals in conditions that more closely approximate their natural habitat and behaviour than a traditional zoo enclosure typically does.

Seed banks are a particularly important ex-situ conservation tool for plant species, especially crop plants, and store the seeds of a very large number of different plant varieties under carefully controlled, low-temperature and low-humidity conditions specifically chosen to keep the seeds viable for extended, often very long, periods of time. Seed banks are especially valuable for conserving the genetic diversity of crop plants because, as described earlier in this chapter, a great deal of the useful genetic variation within a crop species -- genes conferring drought tolerance, disease resistance, or other agriculturally valuable traits -- is held not by any single modern high-yield variety but is distributed across the many older, often now rarely cultivated, traditional and wild-relative varieties of that crop; a seed bank preserves this full range of genetic variation in a stable, easily retrievable form, so that plant breeders can draw on it in the future even if a particular traditional variety has largely disappeared from active cultivation in the field. …