| Conservation status |
|---|
| by risk of extinction |
| Extinct |
| Extinct Extinct in the Wild |
| Threatened |
| Critically Endangered Endangered Vulnerable |
| At lower risk |
| Conservation Dependent Near Threatened Least Concern |
|
See also IUCN Red List International Union for Conservation of Nature |
Functional extinction is the extinction of a species or other taxon such that:
In plant populations, self-incompatibility mechanisms may cause related plant specimens to be incompatible, which may lead to functional extinction if an entire population becomes self incompatible. This does not occur in larger populations.
In polygynous populations, where only a few males leave offspring, there is a much smaller reproducing population than if all viable males were considered. Furthermore, the successful males act as a genetic bottleneck, leading to more rapid genetic drift or inbreeding problems in small populations.
The IUCN Red List does not have a category for functional extinction, and so species which are no longer viable or able to sustain themselves in the wild may be classified as critically endangered; or they may be extinct in the wild if specimens remain in captivity but there is no reasonable doubt that the last wild specimen has died.