Endemism

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The orange-breasted sunbird (Nectarinia violacea) is exclusively found in South African fynbos vegetation. Orange-breasted Sunbird (Nectarinia violacea).jpg
The orange-breasted sunbird (Nectarinia violacea) is exclusively found in South African fynbos vegetation.
Bicolored frog (Clinotarsus curtipes) is endemic to the Western Ghats of India Bicolored Frog ( Clinotarsus curtipes ).jpg
Bicolored frog (Clinotarsus curtipes) is endemic to the Western Ghats of India
Montezuma Well in the Verde Valley of Arizona contains at least five endemic species found exclusively in the sinkhole. Montezuma well - panoramio.jpg
Montezuma Well in the Verde Valley of Arizona contains at least five endemic species found exclusively in the sinkhole.

Endemism is the ecological state of a species being native to a single defined geographic location, such as an island, region, state or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the orange-breasted sunbird is exclusively found in the fynbos vegetation zone of southwestern South Africa and the glacier bear is a subspecies endemic to Southeast Alaska. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. An alternative term for a species that is endemic is precinctive, which applies to species (and other taxonomic levels) that are restricted to a defined geographical area.

Contents

Etymology

The word endemic is from New Latin endēmicus, from Greek ενδήμος, endēmos, "native". Endēmos is formed of en meaning "in", and dēmos meaning "the people". [1] The term "precinctive" has been suggested by some scientists as the equivalent of "endemism", [lower-alpha 1] and was first used in botany by MacCaughey in 1917. [2] Precinction was perhaps first used by Frank and McCoy. [3] [4] Precinctive seems to have been coined by David Sharp when describing the Hawaiian fauna in 1900: "I use the word precinctive in the sense of 'confined to the area under discussion' ... 'precinctive forms' means those forms that are confined to the area specified." [5] This definition (and endemism in general) excludes artificial confinement of examples by humans in far-off botanical gardens or zoological parks.

Overview

Chorus Cicada (Amphipsalta zelandica), a species endemic to New Zealand Chorus cicada.jpg
Chorus Cicada (Amphipsalta zelandica), a species endemic to New Zealand

There are two subcategories of endemism: paleoendemism and neoendemism. 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 through divergence and reproductive isolation or through hybridization and polyploidy in plants, and have yet to disperse beyond a limited range. Charles Darwin's study of neoendemic species in locations like the Galápagos Islands helped form his ideas of evolution by natural selection.

Although the specific drivers of endemism are unclear, physical, climatic, and biological factors can contribute to endemism. Endemic species are especially likely to develop on geographically and biologically isolated areas such as islands and remote island groups, including Hawaii, the Galápagos Islands and Socotra, [6] because of the potential for isolation and therefore evolution through allopatric speciation. Darwin's finches in the Galápagos archipelago and Hydrangea hirta , endemic to Japan, are examples of species endemic to islands. Similarly, isolated mountainous regions like the highlands of Ethiopia, or large bodies of water far from other lakes, like Lake Baikal, can also have high rates of endemism. [7]

The stability of a region's climate and habitat through time may also contribute to high rates of endemism (especially paleoendemism), acting as refuges for species during times of climate change like the Ice Ages. These changes may have caused species to repeatedly restrict their ranges into these refuges, leading to regions with many small-ranged species. [8]

Threats to regions with high endemism

Endemic species can easily become endangered or extinct if their already restricted habitat changes, particularly—but not only—due to human actions, including the introduction of new species. The dodo, a flightless bird species endemic to Mauritius in the Indian Ocean, is a famous example of the vulnerability of endemic species to habitat alteration: the dodo became extinct within decades of the first permanent human settlement on the island in 1638. A dodo was last seen in 1688, ninety years after the birds' first recorded description in 1598. [9]

There were millions of both Bermuda petrels and Bermuda cedars in Bermuda when it was settled at the start of the seventeenth century. By the end of the century, the petrels were thought extinct. Cedars, already ravaged by centuries of shipbuilding, were driven nearly to extinction in the twentieth century by the introduction of a parasite. Bermuda petrels and cedars are now rare, as are other species endemic to Bermuda.[ citation needed ]

Principal causes of habitat degradation and loss in ecosystems with high rates of endemism include agriculture, urban growth, surface mining, mineral extraction, logging operations [10] [11] and slash-and-burn agriculture.

Notes

  1. Precinctivity

Related Research Articles

Adaptive radiation A process in which organisms diversify rapidly from an ancestral species

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, creates new challenges, or opens new environmental niches. Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. The prototypical example of adaptive radiation is finch speciation on the Galapagos, but examples are known from around the world.

Mascarene Islands Archipelago east of Madagascar

The Mascarene Islands or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their name derives from the Portuguese navigator Pedro Mascarenhas, who first visited them in April 1512. The islands share a common geologic origin in the volcanism of the Réunion hotspot beneath the Mascarene Plateau and form a distinct ecoregion with a unique flora and fauna.

A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation.

Insular biogeography or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern of the species–area relationship occurring in oceanic islands. Under either name it is now used in reference to any ecosystem that is isolated due to being surrounded by unlike ecosystems, and has been extended to mountain peaks, seamounts, oases, fragmented forests, and even natural habitats isolated by human land development. The field was started in the 1960s by the ecologists Robert H. MacArthur and E. O. Wilson, who coined the term island biogeography in their inaugural contribution to Princeton's Monograph in Population Biology series, which attempted to predict the number of species that would exist on a newly created island.

Biodiversity of New Zealand The variety of life forms indigenous to New Zealand

The biodiversity of New Zealand, a large island country located in the south-western Pacific Ocean, is varied and distinctive. The species of New Zealand accumulated over many millions of years as lineages evolved in the local circumstances. New Zealand's pre-human biodiversity exhibited high levels of species endemism, but has experienced episodes of biological turnover. Global extinction approximately 65 Ma resulted in the loss of fauna such as non-avian dinosaurs, pterosaurs and marine reptiles e.g. mosasaurs, elasmosaurs and plesiosaurs. The ancient fauna is not well known, but at least one species of terrestrial mammal existed in New Zealand around 19 Ma. For at least several million years before the arrival of human and commensal species, the islands had no terrestrial mammals except for bats and seals, the main component of the terrestrial fauna being insects and birds. Recently—since c. 1300 CE—a component has been introduced by humans, including many terrestrial mammals.

Bermuda petrel

The Bermuda petrel is a gadfly petrel. Commonly known in Bermuda as the cahow, a name derived from its eerie cries, this nocturnal ground-nesting seabird is the national bird of Bermuda and can be found pictured on Bermudian currency. It is the second rarest seabird on the planet and a symbol of hope for nature conservation. They are known for their medium-sized body and long wings. The Bermuda petrel has a greyish-black crown and collar, dark grey upper-wings and tail, white upper-tail coverts and white under-wings edged with black, and the underparts are completely white.

Wildlife of Bermuda

The flora and fauna of Bermuda form part of a unique ecosystem due to Bermuda's isolation from the mainland of North America. The wide range of endemic species and the islands form a distinct ecoregion, the Bermuda subtropical conifer forests.

Galápagos petrel

The Galápagos petrel is one of the six endemic seabirds of the Galápagos. Its scientific name derives from Ancient Greek: Pterodroma originates from pteron and dromos, meaning "wing" and "runner", and phaeopygia comes from phaios and pugios, meaning "dusky" and "rump". Members of Pterodroma genus are also called the gadfly petrels because their erratic twisting and turning in flight resemble that of gadflies.

Hawaiian petrel Species of bird

The Hawaiian petrel or ʻuaʻu is a large, dark grey-brown and white petrel that is endemic to Hawaiʻi.

Fauna of Puerto Rico Animals found in the United States Territory of Puerto Rico

The fauna of Puerto Rico is similar to other island archipelago faunas, with high endemism, and low, skewed taxonomic diversity. Bats are the only extant native terrestrial mammals in Puerto Rico. All other terrestrial mammals in the area were introduced by humans, and include species such as cats, goats, sheep, the small Asian mongoose, and escaped monkeys. Marine mammals include dolphins, manatees, and whales. Of the 349 bird species, about 120 breed in the archipelago, and 47.5% are accidental or rare.

Fauna of Ghana

The wildlife of Ghana is composed of its biodiversity of flora and fauna.

Cyprinodon longidorsalis, the cachorrito de charco palmal or La Palma pupfish, is a species of fish in the family Cyprinodontidae. It was endemic to the Ojo de Agua la Presa in southwestern Nuevo Leon state in Mexico, but became extinct in the wild in 1994 due to habitat loss. The same freshwater spring system was the home of three other pupfish: Cyprinodon ceciliae (extinct), Cyprinodon inmemoriam (extinct) and Cyprinodon veronicae. Although these were from the same spring system, each was restricted to its own individual spring pool. The Charco La Palma pool and its spring had a combined area of about 10 m2 (110 sq ft) and was no more than 1.4 m at the deepest point, making the range of the La Palma pupfish perhaps the smallest known for any vertebrate species. This tiny spring pond also was the home of a now-extinct, undescribed species of Cambarellus crayfish.

Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability of empty niches lead to increased speciation. As a result, island ecosystems comprise 30% of the world’s biodiversity hotspots, 50% of marine tropical diversity, and some of the most unusual and rare species. Many species still remain unknown.

Julian P. Hume

Julian Pender Hume is an English palaeontologist, artist and writer who lives in Wickham, Hampshire. He was born in Ashford, Kent, and grew up in Portsmouth, England. He attended Crookhorn Comprehensive School between 1971 and 1976. His career began as an artist, specialising in the reconstruction of extinct species, after which he undertook a degree in palaeontology at the University of Portsmouth, followed by a PhD in the same subject, jointly hosted by the University of Portsmouth and the Natural History Museum, London and Tring. He is presently a Research Associate at the Natural History Museum, and has travelled extensively, working on fossil excavations that include the Cape Verde Islands; Lord Howe Island, Tasmania, Flinders, King and Kangaroo Islands, Australia; Madagascar, Seychelles, and Hawaiian Islands. However, his main area of research is the Mascarene Islands of Mauritius, Réunion, and Rodrigues, where in particular he has studied the history of the dodo.

Paleoendemism along with neoendemism is one of two sub-categories 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 through divergence and reproductive isolation or through hybridization and polyploidy in plants.

In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population that currently occurs in a restricted area, but whose original range was far wider during a previous geologic epoch. Similarly, a relictual taxon is a taxon that is the sole surviving representative of a formerly diverse group.

Neoendemism is one of two sub-categories of endemism, the ecological 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 in plants. Paleoendemism, the other sub-category, refers to species that were formerly widespread but are now restricted to a smaller area.

References

  1. "Endemic". Reference.com. Retrieved 6 December 2014.
  2. MacCaughey V (August 1917). "A survey of the Hawaiian land flora". Botanical Gazette. LXIV (2): 92. doi:10.1086/332097.
  3. Frank JH, McCoy ED (March 1990). "Endemics and epidemics of shibboleths and other things causing chaos". Florida Entomologist. 73 (1): 1–9. JSTOR   3495327.
  4. Frank JH, McCoy ED (March 1995). "Precinctive insect species in Florida". Florida Entomologist. 78 (1): 21–35. doi: 10.2307/3495663 . JSTOR   3495663. [also uses word precinction]
  5. Sharp D (1900). "Coleoptera. I. Coleoptera Phytophaga". In Sharp D (ed.). Fauna Hawaiiensis, Being the Land-Fauna of the Hawaiian Islands. 2 part 3. Cambridge: Cambridge Univ. Press. pp. 91–116.
  6. Kier G, Kreft H, Lee TM, Jetz W, Ibisch PL, Nowicki C, Mutke J, Barthlott W (June 2009). "A global assessment of endemism and species richness across island and mainland regions". Proceedings of the National Academy of Sciences of the United States of America. 106 (23): 9322–7. Bibcode:2009PNAS..106.9322K. doi:10.1073/pnas.0810306106. PMC   2685248 . PMID   19470638.
  7. Steinbauer MJ, Field R, Grytnes JA, Trigas P, Ah-Peng C, Attorre F, et al. (2016). "Topography-driven isolation, speciation and a global increase of endemism with elevation" (PDF). Global Ecology and Biogeography. 25 (9): 1097–1107. doi:10.1111/geb.12469.
  8. Harrison S, Noss R (January 2017). "Endemism hotspots are linked to stable climatic refugia". Annals of Botany. 119 (2): 207–214. doi:10.1093/aob/mcw248. PMC   5321063 . PMID   28064195.
  9. Hume JP, Martill DM, Dewdney C (June 2004). "Palaeobiology: Dutch diaries and the demise of the dodo". Nature. 429 (6992): 1 p following 621. Bibcode:2004Natur.429.....H. doi:10.1038/nature02688. PMID   15190921. S2CID   4343538.
  10. Smiet F (June 1982). "Threats to the Spice Islands". Oryx. 16 (4): 323–328. doi:10.1017/S0030605300017774.
  11. Foley JA, Asner GP, Costa MH, Coe MT, DeFries R, Gibbs HK, et al. (February 2007). "Amazonia revealed: forest degradation and loss of ecosystem goods and services in the Amazon Basin". Frontiers in Ecology and the Environment. Ecological Society of America. 5 (1): 25–32. doi:10.1890/1540-9295(2007)5[25:ARFDAL]2.0.CO;2. S2CID   15798898.

Further reading