Neoendemism is one of two sub-categories of

endemism Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

, the

ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

state of a species being unique to a defined geographic location. Specifically, neoendemic species are those that have recently arisen, through divergence and reproductive isolation or through hybridization and

polyploidy Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...

in plants. Paleoendemism, the other sub-category, refers to species that were formerly widespread but are now restricted to a smaller area.

Examples

Darwin's finches Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for being a classic example of adaptive radiation and for their remarkable diversity in beak form and function. They ...

", residents of the

Galápagos Islands The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

, have been used since the 19th century as an example of how the descendants of one ancestor can evolve through adaptive radiation into several species as they adapt to different conditions on various islands. Charles Darwin wrote:

...one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."

The Galápagos archipelago is also the home of paleoendemic species. The Santa Cruz cypress (''Hesperocyparis abramsiana''; formerly classified as ''Cupressus abramsiana'') has a geographic range limited to a small section in the

Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles (120 km), accessible via California S ...

region of

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

where subsea canyon topography reliably produces summer fog, owing to cold water upwelling. The U.S. Fish and Wildlife Service listed the species as endangered in 1987, due to increasing threats from habitat loss and disruption of natural forest fire regimes.U.S. Fish and Wildlife Service. 1987. Endangered and threatened wildlife and plants; Determination of endangered status for ''Cupressus abramsiana'' (Santa Cruz cypress). Federal Register 52: 675-679. https://ecos.fws.gov/docs/federal_register/fr1017.pdf In 2016, the conservation status of the Santa Cruz cypress was reduced to threatened. The cited reasoning was a decrease in threats against their habitat.U.S. Fish and Wildlife Service. 2016. Endangered and Threatened Wildlife and Plants; Reclassifying ''Hesperocyparis abramsiana'' (=''Cupressus abramsiana'') as Threatened. Federal Register Vol. 81. No. 33. https://www.govinfo.gov/link/fr/81/8408?link-type=pdf However, a lengthy section of the 2016 federal report titled "Genetic introgression" (also known as introgressive hybridization) explains how the integrity of this species is also threatened by nearby horticultural plantings of a sister species, Monterey cypress, whose historically native range is nearby: on the opposite side of Monterey Bay. Hybridization is known to occur between the two endemics — as well as with a widely planted sister species native to Arizona: Arizona cypress. The ease of hybridization of cypress species in the

American southwest The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural list of regions of the United States, region of the United States that includes Arizona and New Mexico, along with adjacen ...

has fostered a parallel history of taxonomic disagreements of where genus and species distinctions should apply. It thus provides a case study of neoendemism in conifers. As well, it illustrates an element of ongoing human impact — wind-dispersed pollen contamination from horticultural plantings — that cannot easily be corrected to meet conservation goals.

Notes

References

* * {{Citation , last= Darwin , first= Francis , author-link= Francis Darwin , date=1887 , contribution=Chapter 1, The Foundations of the 'Origin of Species' , contribution-url=http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.2&pageseq=21 , editor-last= Darwin , editor-first= Francis , title=The life and letters of Charles Darwin, including an autobiographical chapter , location=London , publisher=John Murray , volume=2, issue= 2 , page= 141 , pmc=2604052 Endemism

Examples

See also

Notes

References