Despeciation is the loss of a unique species of animal due to its combining with another previously distinct species. It is the opposite of

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution withi ...

and is much more rare. It is similar to extinction in that there is a loss of a unique

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

but without the associated loss of a biological lineage. Despeciation has been noted in species of butterflies, sunflowers, mosquitoes, fish, wolves, and even humans.

Examples

North American ravens

Holarctic ravens and Californian ravens had been two separate species for 1.5 million years until tens of thousands of years ago when their regions overlapped and they began to merge into a new species. This new raven species contains genes coming from both the Holarctic and Californian raven. This was possible because they occupy the same area of the Western United States.

Three-spined sticklebacks

Another possible cause for despeciation is increased gene flow and hybridization due to changes in the environment. One of these changes could include the loss of essential nourishment resources for each individual species. For example, Taylor et al.'s genetic analysis of

three-spined stickleback The three-spined stickleback (''Gasterosteus aculeatus'') is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its ra ...

s across six lakes in southwestern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

found two distinct species in 1977 and 1988 but only one combined species in data from 1997, 2000, and 2002. The new species is a hybrid and shows an intermediate form of the parental genotype. They concluded that external factors had imperiled the living conditions of the two species, thus eliminating the evolutionary specializations that had kept them unique.

Humans

Anatomically modern humans Early modern human (EMH) or anatomically modern human (AMH) are terms used to distinguish ''Homo sapiens'' (the only extant Hominina species) that are anatomically consistent with the range of phenotypes seen in contemporary humans from extin ...

(''Homo sapiens'') are considered to have undergone despeciation due to the genomes associated with remains of the closest

archaic human A number of varieties of ''Homo'' are grouped into the broad category of archaic humans in the period that precedes and is contemporary to the emergence of the earliest early modern humans (''Homo sapiens'') around 300 ka. Omo-Kibish I (Omo I) ...

species to modern humans, such as the

Denisovans The Denisovans or Denisova hominins ) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. Denisovans are known from few physical remains and consequently, most of what is kn ...

and Neanderthals, among others. These genomes show that human ancestors interbred with these other hominins. Genes identified as being of Neanderthal and Denisovan origin have been located in the genome of modern humans in varying amounts dependent on location, and one Neanderthal-Denisovan hybrid nicknamed

Denny Denny or Dennie may refer to: People *Denny (given name), a list of people named Denny or Dennie *Denny (surname), a list of people surnamed Denny or Dennie *Denny (hybrid hominin) Places *Denny, California, a ghost town *Denny, Falkirk, a town i ...

has been identified, indicating that interbreeding took place where populations of the three species met.

References

{{Extinction , state=autocollapse Evolution Speciation