Functional extinction is the

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

of a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

or other

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

such that: #It disappears from the

fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, or historic reports of its existence cease; #The reduced population no longer plays a significant role in

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

function; #The population is no longer viable. There are no individuals able to reproduce, or the small population of breeding individuals will not be able to sustain itself due to

inbreeding depression Inbreeding depression is the reduced biological fitness caused by loss of genetic diversity as a consequence of inbreeding, the breeding of individuals closely related genetically. This loss of genetic diversity results from small population siz ...

and

genetic drift Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, is the change in the Allele frequency, frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene va ...

, which leads to a loss of fitness. 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.

Functionally extinct species in modern times

* Baiji * Northern white rhinoceros * Ivory-billed woodpecker * Imperial woodpecker * Christmas Island shrew * Yangtze giant softshell turtle * South China tiger *

Barbary lion The Barbary lion was a population of the lion subspecies '' Panthera leo leo''. It was also called North African lion, Atlas lion, and Egyptian lion. It lived in the mountains and deserts of the Maghreb of North Africa from Morocco to Egypt. It ...

* Bornean rhinoceros * Vaquita * Fernandina Island tortoise *'' Hyophorbe amaricaulis'' *

North Atlantic right whale The North Atlantic right whale (''Eubalaena glacialis'') is a baleen whale, one of three right whale species belonging to the genus ''Eubalaena'', all of which were formerly classified as a single species. Because of their docile nature, their sl ...

On May 10, 2019, the Australian Koala Foundation issued a

press release A press release (also known as a media release) is an official statement delivered to members of the news media for the purpose of providing new information, creating an official statement, or making an announcement directed for public releas ...

that opened with the sentence "The Australian Koala Foundation (AKF) believes Koalas may be functionally extinct in the entire landscape of Australia." The press release was reported on by multiple news agencies around the world, with most repeating the AKF's statement. Despite this,

koala The koala (''Phascolarctos cinereus''), sometimes inaccurately called the koala bear, is an arboreal herbivorous marsupial native to Australia. It is the only Extant taxon, extant representative of the Family (biology), family ''Phascolar ...

s are not currently considered functionally extinct; while their population has decreased, the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

lists them only as " Vulnerable". The AKF's press release was released on the eve of the 2019 elections in Australia, where topics such as

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

were major issues. Distinct animal populations can also become functionally extinct. In 2011, a 3-year survey of the wildlife population in the Bénoué Ecosystem of North Cameroon (the Bénoué, Bouba-Ndjidda, and Faro national parks, and 28 hunting zones surrounding the parks), concluded that the North Cameroon population of

cheetah The cheetah (''Acinonyx jubatus'') is a large Felidae, cat and the Fastest animals, fastest land animal. It has a tawny to creamy white or pale buff fur that is marked with evenly spaced, solid black spots. The head is small and rounded, wit ...

s (''Acinonyx jubatus'') and African wild dogs (''Lycaon pictus'') were now functionally extinct. Non-Northern Cameroonian cheetahs are listed as "Vulnerable" by the

References

{{Extinction Extinction

Functionally extinct species in modern times

See also

References