Endemism in the Hawaiian Islands

Located about 2300 miles (3680 km) from the nearest continental shore, the Hawaiian Islands are the most isolated group of islands on the planet. The plant and animal life of the Hawaiian archipelago is the result of early, very infrequent colonizations of arriving species and the slow evolution of those species—in isolation from the rest of the world's flora and fauna—over a period of at least 5 million years. As a consequence, Hawai'i is home to a large number of endemic species. The radiation of species described by Charles Darwin in the Galapagos Islands which was critical to the formulation of his theory of evolution is far exceeded in the more isolated Hawaiian Islands.

The relatively short time that the existing main islands of the archipelago have been above the surface of the ocean (less than 10 million years) is only a fraction of time span over which biological colonization and evolution have occurred in the archipelago. High, volcanic islands have existed in the Pacific far longer, extending in a chain to the northwest; these once mountainous islands are now reduced to submerged banks and coral atolls. Midway Atoll, for example, formed as a volcanic island some 28 million years ago. Kure Atoll, a little further to the northwest, is near the Darwin point—defined as waters of a temperature that allows coral reef development to just keep up with isostatic sinking. And extending back in time before Kure, an even older chain of islands spreads northward nearly to the Aleutian Islands; these former islands, all north of the Darwin point, are now completely submerged as the Emperor Seamounts.

The islands are well known for the environmental diversity that occurs on high mountains within a trade winds field. On a single island, the climate can differ around the coast from dry tropical (< 20 in or 500 mm annual rainfall) to wet tropical; and up the slopes from tropical rainforest (> 200 in or 5000 mm per year) through a temperate climate into alpine conditions of cold and dry climate. The rainy climate impacts soil development, which largely determines ground permeability, which affects the distribution of streams, wetlands, and wet places.

The distance and remoteness of the Hawaiian archipelago is a biological filter. Seeds or spores attached to a lost migrating bird's feather or an insect falling out of the high winds found a place to survive in the islands and whatever else was needed to reproduce. The narrowing of the gene pool meant that at the very beginning, the population of a colonizing species was a bit different from that of the remove, contributing population.

Island formation

Throughout time, the Hawaiian Islands formed linearly from northwest to the southeast. A study was conducted to determine the approximate ages of the Hawaiian Islands using K–Ar dating of the oldest found igneous rocks from each island. Kauai was determined to be about 5.1 million years old, Oahu about 3.7 million years old and the youngest island of Hawaii about 0.43 million years old.[1] By determining the maximum age of the islands, inferences could be made about the maximum possible age of organisms inhabiting the island. The newly formed islands were able to accommodate growing populations, while the new environments were causing high rates of new adaptations.

Human arrival

Human contact, first by Polynesians and later by Europeans, has had a significant impact. Both the Polynesians and Europeans cleared native forests and introduced non-indigenous species for agriculture (or by accident), driving many endemic species to extinction. Fossil finds in caves, lava tubes, and sand dunes have revealed an avifauna that once had a native eagle,[2] two raven-size crows, several bird-eating owls, and giant ducks known as moa-nalos.

Today, many of the remaining endemic species of plants and animals in the Hawaiian Islands are considered endangered, and some critically so. Plant species are particularly at risk: out of a total of 2,690 plant species, 946 are non-indigenous with 800 of the native species listed as endangered.[3]

A list of endemic species of Hawaiʻi

Following is a list featuring mammal, bird, fish, invertebrate and plant species endemic to the island chain -- both extant and extinct species for each category. Note that, simply because of the relatively small area involved, many Hawaiian species are considered threatened even when at their normal population levels.

Mammals

Birds

Freshwater fishes

None of Hawaii's native fish are entirely restricted to freshwater (all are either anadromous, or also found in brackish and marine water in their adult stage).

Invertebrates

Insects

Crustaceans

  • Atyoida bisulcata (a freshwater shrimp)
  • Halocaridina (a genus of marine and brackish water shrimp)
  • Hawaiian river shrimp (Macrobrachium grandimanus)

Spiders

Gastropods

  • Oahu tree snails (Achatinella) - threatened, several already extinct
  • Auriculella (a genus of land snails) - threatened, several already extinct
  • Erinna (a genus of freshwater snails) - one vulnerable species, the other possibly extinct
  • Gulickia alexandri (a land snail) - critically endangered
  • Newcombia (a genus of land snails) - threatened, one already extinct
  • Neritina granosa (a freshwater snail) - vulnerable
  • Perdicella (a genus of land snails) - threatened, several already extinct

[5]

Cnidarians

  • Finger coral (Porites compressa)
  • Thick finger coral (Porites duerdeni)
  • Brigham's coral (Porites brighami)
  • Molokaʻi cauliflower coral (Pocillopora molokensis)
  • Irregular rice coral (Montipora dilatata)
  • Blue rice coral (Montipora flabellata)
  • Sandpaper rice coral (Montipora patula)
  • Verril's lump coral (Psammocora verrilli)
  • Serpentine cup coral (Eguchipsammia serpentina)
  • Grand black coral (Antipathes grandis)
  • Bicolor gorgonian (Acabaria bicolor)
  • Small knob leather coral (Sinularia molokaiensis)

Plants

See also

References

  1. ^ Fleischer, RC; McIntosh, CE; Tarr, CL (1998). "Evolution on a volcanic conveyor belt: using phylogeographic reconstructions and K–Ar-based ages of the Hawaiian islands to estimate molecular evolutionary rates". Molecular Ecology (7): 533–45.
  2. ^ Fleischer, Robert; Olsen, Storrs; James, Helen; Cooper, Alan (October 2000). "Identification of the Extinct Hawaiian Eagle (Haliaeetus) by mtDNA Sequence Analysis" (PDF). The Auk. Retrieved May 23, 2018.
  3. ^ David Pimentel; Lori Lach; Rodolfo Zuniga & Doug Morrison (January 24, 1999), "Environmental and Economic Costs Associated with Non-Indigenous Species in the United States", Cornell Chronicle, Cornell University, retrieved April 3, 2015
  4. ^ Lindstrom, D.P., M.J. Blum, R.P. Walter, R.B. Gagne and J.F. Gilliam, 2012. Molecular and morphological evidence of distinct evolutionary lineages of Awaous guamensis in Hawai’i and Guam. Copeia (2):293-300.
  5. ^ Fenner, Douglas (2005). Corals of Hawai'i : field guide to the hard, black, and soft corals of Hawai'i and the northwest Hawaiian Islands, including Midway (1 ed.). Honolulu, Hawai'i: Mutual Pub. ISBN 1-56647-673-9.

Further reading

External links

Environment of Hawaii

Hawaii is one of fifty states of the U.S. and covers the Hawaiian Islands, a volcanic archipelago consisting of eight major islands, several atolls and numerous smaller islets. Hawaii became a state of the United States in 1959. Prior to that it was the Territory of Hawaii (1898 to 1959) and originally the Kingdom of Hawaii.

List of Lepidoptera of Hawaii

An estimated 1,150 species of Lepidoptera, the order comprising butterflies and moths, have been recorded in the U.S. state of Hawaii. Of these, 948 are endemic and 199 are nonindigenous species.

This page provides a link to either individual species or genera. The latter is used when all species of the genus are endemic to Hawaii, the individual species can be found on the genus page.

List of endemic birds of Hawaii

There are 71 known taxa of birds endemic to the Hawaiian Islands, of which 30 are extinct, 6 possibly extinct and 30 of the remaining 48 species and subspecies are listed as endangered or threatened by the United States Fish and Wildlife Service. Habitat loss and avian disease are thought to have had the greatest effect on endemic bird species in Hawaii.

List of extinct animals of the Hawaiian Islands

This is an incomplete list of extinct animals of the Hawaiian Islands.

Mauna Kea

Mauna Kea ( or , Hawaiian: [ˈmɐwnə ˈkɛjə]) is a dormant volcano on the island of Hawaii. Its peak is 4,207.3 m (13,803 ft) above sea level, making it the highest point in the state of Hawaii. Most of the volcano is underwater, and when measured from its underwater base, Mauna Kea is the tallest mountain in the world, measuring over 10,000 m (33,000 ft) in height. Mauna Kea is about a million years old, and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, resulting in a steeper profile. Late volcanism has also given it a much rougher appearance than its neighboring volcanoes due to construction of cinder cones, decentralization of its rift zones, glaciation on its peak, and weathering by the prevailing trade winds. Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant. The peak is about 38 m (125 ft) higher than Mauna Loa, its more massive neighbor.

In Hawaiian mythology, the peaks of the island of Hawaii are sacred. An ancient law allowed only high-ranking aliʻi to visit its peak. Ancient Hawaiians living on the slopes of Mauna Kea relied on its extensive forests for food, and quarried the dense volcano-glacial basalts on its flanks for tool production. When Europeans arrived in the late 18th century, settlers introduced cattle, sheep and game animals, many of which became feral and began to damage the volcano's ecological balance. Mauna Kea can be ecologically divided into three sections: an alpine climate at its summit, a Sophora chrysophylla–Myoporum sandwicense (or māmane–naio) forest on its flanks, and an Acacia koa–Metrosideros polymorpha (or koa–ʻōhiʻa) forest, now mostly cleared by the former sugar industry, at its base. In recent years, concern over the vulnerability of the native species has led to court cases that have forced the Hawai'i Department of Land and Natural Resources to eradicate all feral species on the volcano.

With its high elevation, dry environment, and stable airflow, Mauna Kea's summit is one of the best sites in the world for astronomical observation. Since the creation of an access road in 1964, thirteen telescopes funded by eleven countries have been constructed at the summit. The Mauna Kea Observatories are used for scientific research across the electromagnetic spectrum and comprise the largest such facility in the world. Their construction on a landscape considered sacred by Native Hawaiians continues to be a topic of debate to this day.

Orsonwelles

Orsonwelles is a genus of American dwarf spiders that was first described by G. Hormiga in 2002. They are all native to the Hawaiian Islands, each species occurring on a single island, often at high elevations. Many of the species names commemorate elements from Welles' films, radio productions, or roles. One species has not been collected since the 1890s, and is believed to be extinct. The name honors the actor and film-maker Orson Welles.

The first species were described in 1900 by the French naturalist Eugène Simon, who described Orsonwelles malus (as Labulla torosa) and Orsonwelles graphicus (as Labulla graphica). In 2002, Gustavo Hormiga described eleven new species, establishing the new genus Orsonwelles. The Labulla species became torosus and graphicus because Orsonwelles is a masculine noun.

Outline of Hawaii

The following outline is provided as an overview of and topical guide to the U.S. state of Hawaii:

Hawaii is the newest state among the 50 states of the United States of America. It is also the southernmost state, the only tropical state, and the only state that was previously an independent monarchy. The state comprises the Hawaiian Islands (with the exception of Midway) in the North Pacific Ocean and is the only U.S. state that is not primarily located on the continent of North America.

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