Neoendemism is one of two sub-categories of

endemism Endemism is the state of a species being found 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 found elsew ...

, the

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

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 one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

in plants.

Paleoendemism Paleoendemism along with neoendemism is a possible subcategory of endemism. Paleoendemism refers to species that were formerly widespread but are now restricted to a smaller area. Neoendemism refers to species that have recently arisen, such as thro ...

, 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 their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or t ...

", residents of the

Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...

, have been used since the 19th century as an example of how the descendants of one ancestor can evolve through

adaptive radiation In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic int ...

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 and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by a ...

region of

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

where subsea canyon topography reliably produces summer fog, owing to cold water upwelling. The

U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with oth ...

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 Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...

) explains how the integrity of this species is also threatened by nearby horticultural plantings of a sister species,

Monterey cypress ''Hesperocyparis macrocarpa'' is a coniferous tree. It is commonly known as the Monterey cypress and is one of several species of cypress trees endemic to California. The Monterey cypress is found naturally only on the Central Coast of Califor ...

, 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 ''Cupressus arizonica'', the Arizona cypress, is a North American species of tree in the cypress family Cupressaceae, native to the southwestern United States and Mexico. Populations may be scattered rather than in large, dense stands. Descripti ...

. 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 region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, N ...

has fostered a parallel history of

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

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, pmc=2604052 Endemism

Examples

See also

Notes

References