濒危动物 Endangered species
An endangered species is a population of an organism (usually a taxonomic species), which because it is either (a) few in number or (b) threatened by changing environmental or predation parameters, is at risk of becoming extinct. Many countries have laws offering special protection to these species or their habitats: for example, forbidding hunting, restricting land development or creating preserves. Only a few of the many endangered species actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially will become extinct, without gaining public notice.
The greatest factor of concern is the rate at which species are becoming extinct within the last 150 years. While species have evolved and become extinct on a regular basis for the last several hundred million years, the number of species becoming extinct since the Industrial Revolution has no precedent in biological history. If this rate of extinction continues, or accelerates as now seems to be the case, the number of species becoming extinct in the next decade could number in the millions[1]. While most people readily relate to endangerment of large mammals or birdlife, some of the greatest ecological issues are the threats to stability of whole ecosystems if key species vanish at any level of the food chain.
Species extinction is the ultimate concern, but there are four different reasons to have for concern with this outcome:
Loss of a species as a biological entity;
destabilization of an ecosystem;
endangerment of other species;
loss of irreplaceable genetic material and associated biochemicals.
The loss of a species in and of itself is an important factor, both as diminution of the enjoyment of nature and as a moral issue for those who believe humans are stewards of the natural environment. Destabilization is a well understood outcome, when an element of food or predation is removed from an ecosystem. Examples abound that other species are in turn affected, such that population increases or declines are forthcoming in these secondary species. Marked change or an unstable spiral can ensue, until other species are lost and the ecosystem structure is changed markedly and irreversibly.
The fourth outcome is more subtle, but perhaps the most important point for mankind to grasp. Each species carries unique genetic material in its DNA and in its chemical factory responding to these genetic instructions. For example, in the valleys of central China, a fernlike weed called sweet wormwood grows, that is the only source of artemisinin, a drug that is nearly 100 percent effective against malaria (Jonietz, 2006). If this plant were lost to extinction, then the ability to control malaria, even today a potent killer, would diminish. There are countless other examples of chemicals unique to a certain species, whose only source is the species, whose genetic factory makes that given substance. How many further chemicals have not yet been discovered and could vanish from the planet when further species become extinct cannot be determined, but it is a highly debated and influential point.
Though extinction can be a natural effect of the process of natural selection, the current extinction crisis is not related to that process. At the present, the Earth has fallen from a peak of biodiversity[1] and Earth is undergoing the Holocene mass extinction period.[2] These periods have occurred before without human intervention; however the current extinction period is unique. Previous periods were triggered by physical causes, such as meteorite collision and volcanic eruption, all leading to climate change. The current extinction period is being caused by humans and began approximately 100,000 years ago with the diaspora of humans to different parts the world. By entering new ecosystems which had never before experienced the human presence, humans disrupted the ecological balance by hunting and also possibly bringing disease. From this time up to approximately 10,000 years ago is known as "phase one" of the sixth extinction period.
Phase two of the period began approximately 10,000 years ago with the birth of agriculture. With the birth of agriculture, humans did not have to rely on interaction with other species for survival and so could begin to domesticate them, and they also did not have to adhere to the limitations of the ecosystem's carrying capacity. Thus, humans became the first species able to live outside local ecosystems. As Niles Eldridge says "Indeed, to develop agriculture is essentially to declare war on ecosystems - converting land to produce one or two food crops, with all other native plant species all now classified as unwanted "weeds" -- and all but a few domesticated species of animals now considered as pests."[3] With the ability to live outside of a local ecosystem, humans have been free to breech the "carrying-capacity" of areas and overpopulate, putting ever more stress on the environment with destructive activities necessary for more population growth. Today, those activities include tropical deforestation, coral loss, other habitat destruction, overexploitation of species, introduction of alien species into ecosystems and pollution (such as soil contamination and greenhouse gases).
[edit] Conservation status
The conservation status of a species is an indicator of the likelihood of that endangered species continuing to survive. Many factors are taken into account when assessing the conservation status of a species; not simply the number remaining, but the overall increase or decrease in the population over time, breeding success rates, known threats, and so on. In many areas this is referred to as a red-listed species. Internationally, 189 countries have signed an accord agreeing to create Biodiversity Action Plans to protect endangered and other threatened species. In the USA this plan is usually called a species Recovery Plan.
The best-known worldwide conservation status listing is the IUCN Red List, but many more specialized lists exist. The following conservation status categories are used in articles in this encyclopedia. They are loosely based on the IUCN categories.
Extinct: the last remaining member of the species had died, or is presumed beyond reasonable doubt to have died. Examples: Thylacine, Dodo, Passenger Pigeon.
Extinct in the wild: captive individuals survive, but there is no free-living, natural population. Examples: Dromedary.
Critical or critically endangered: faces an extremely high risk of extinction in the immediate future. Examples: Ivory-billed Woodpecker, Arakan Forest Turtle
Endangered: faces a very high risk of extinction in the near future. Examples: Blue Whale, Snow Leopard, Kings holly
Vulnerable: faces a high risk of extinction in the medium-term. Examples: Cheetah, Bactrian Camel
Secure or lower risk: no immediate threat to the survival of the species. Examples: Norway Rat, Nootka Cypress, Llama
The following lists are examples of endangered species. It is important to stress that the following lists are a miniscule fraction of the total endangered species. It is also worth noting that the number of species becoming extinct each year is many times as large as the number of species classified as endangered; this fact arises from the extensive and slow review process for listing new species as endangered. It also arises from the voluminous number of yearly extinctions, often for species about which little documentation exists. Note that because of varying standards for regarding a species as endangered, and the very large number of endangered species, these lists should not be regarded as comprehensive. neha
[edit] Endangered mammals
The endangered Island FoxThe following list is a very small fraction of known endangered mammals:
Asian Elephant (Elephas maximus)
Aye-aye (Daubentonia madagascariensis)
Banteng (Bos javanicus)
Bighorn Sheep (Ovis canadensis)
Black Rhinoceros (Diceros bicornis)
Black-footed Ferret (Mustela nigripes)
Black-tailed Prairie Dog (Cynomys ludovicianus)
Blue Whale (Balaenoptera musculus)
Bonobo (Pan paniscus)
Bornean Orangutan (Pongo pygmaeus)
Bowhead Whale (Balaena mysticetus)
Brazilian Sloth (Bradypus torquatus)
Burrowing Bettong (Bettongia lesueur nova)
Common Chimpanzee (Pan troglodytes)
Chinese River Dolphin (Lipotes vexillifer) and other river dolphins
Diademed Sifaka (Propithecus diadema)
Eastern Gorilla (Gorilla beringei)
The endangered Sea OtterFin Whale (Balaenoptera physalus)
Forest Elephant (Loxodonta cyclotis)
Fossa (Cryptoprocta ferox)
Gelada (Theropithecus gelada)
Giant golden-crowned flying fox (Acerodon jubatus)
Giant otter (Pteronura brasiliensis)
Giant Panda (Ailuropoda melanoleuca)
Giant Pangolin (Manis gigantea)
Giant Sable Antelope (Hippotragus niger varani)
Golden Lion Tamarin (Leontopithecus rosalia)
Gray Bat (Myotis grisescens)
Hawaiian Monk Seal (Monachus schauinslandi)
Humpback Whale (Megaptera novaeangliae)
Iberian Lynx (Lynx pardinus)
Indian Pangolin (Manis crassicaudata)
Indri (Indri indri)
Island Fox (Urocyon littoralis)
Javan Rhinoceros (Rhinoceros sondaicus)
Humpback WhaleKey Deer (Odocoileus virginianus clavium)
Kouprey (Bos sauveli)
Leopard (Panthera pardus)
Mahogany Glider (Petaurus gracilis)
Mountain Pygmy Possum (Burramys parvus)
Northern Hairy-nosed Wombat (Lasiorhinus krefftii)
Numbat (Myrmecobius fasciatus)
Ocelot (Leopardus pardalis)
Père David's Deer (Elaphurus davidianus)
Proboscis Monkey (Nasalis larvatus)
Red Panda (Ailurus fulgens)
Red Wolf (Canis rufus)
American bison skull heap. There were as few as 750 bison in 1890 from overhunting.Savannah Elephant (Loxodonta africana)
Sea Otter (Enhydra lutris)
Sei Whale (Balaenoptera borealis)
Snow Leopard (Uncia uncia)
Steller's Sea Lion (Eumetopias jubatus)
Sumatran Orangutan (Pongo abelii)
Sumatran Rhinoceros (Dicerorhinus sumatrensis)
Temminck's Pangolin (Manis temminckii)
Tibetan Antelope (Pantholops hodgsonii)
Tiger (Panthera tigris)
Timber Wolf (Canis lupus)
Vaquita (Phocoena sinus)
Western Gorilla (Gorilla gorilla)
West Indian Manatee (Trichechus manatus)
Wolverine (Gulo gulo)
[edit] Endangered birds
Immature California CondorAlaotra Grebe (Tachybaptus rufolavatus)
Andean Condor (Vultur gryphus)
Amami Thrush (Zoothera major)
Amsterdam Albatross (Diomedea amsterdamensis)
Attwater's prairie-chicken (Tympanuchus cupido attwateri)
Bali Starling (Leucospar rothschildi)
Black-capped Petrel (Pterodroma hasitata)
Bornean Peacock Pheasant (Polyplectron schleiermacheri)
Brazilian Merganser (Mergus octosetaceus)
California Clapper Rail (Rallus longirostris obsoletus)
California Least Tern (Sterna antillarum browni)
California Condor (Gymnogyps californianus)
Chatham Albatross (Thalassarche eremita)
Chinese Crested Tern (Sterna bernsteinii)
Christmas Island Frigatebird (Fregata andrewsi)
Cozumel Thrasher (Toxostoma guttatum)
Crested Ibis (Nipponia nippon)
Eskimo Curlew (Numenius borealis)
Giant Ibis (Thaumatibis gigantea)
Glaucous Macaw (Anodorhynchus glaucus)
Guam Rail (Gallirallus owstoni)
Gurney's Pitta (Pitta gurneyi)
Hawaiian Crow (Corvus hawaiiensis)
Hawaiian Goose or Néné (Branta sandvicensis)
Imperial Woodpecker (Campephilus imperialis)
Indian White-rumped Vulture (Gyps bengalensis)
Ivory-billed Woodpecker (Campephilus principalis)
Jerdon's Courser (Rhinoptilus bitorquatus)
Junin Flightless Grebe (Podiceps taczanowskii)
Kagu (Rhynochetos jubatus)
Kakapo (Strigops habroptilus)
Kittlitz's Murrelet (Brachyramphus brevirostris)
Kiwi (Apteryx australis, A. hastii, A. owenii)
Laysan Duck (Anas laysanensis)
Lear's Macaw (Anodorhynchus leari)
Long-billed Vulture (Gyps indicus)
Magdalena Tinamou (Crypturellus saltuarius)
Magenta Petrel (Pterodroma magentae)
Maleo (Macrocephalon maleo)
Mauritius Fody (Foudia rubra)
Mauritius Parakeet (Psittacula eques)
Mindoro Bleeding-heart (Gallicolumba platenae)
New Zealand Storm-petrel (Oceanites maorianus)
Night Parrot (Geopsittacus occidentalis)
Northern Bald Ibis (Geronticus eremita)
Okinawa Woodpecker (Sapheopipo noguchii)
Orange-bellied Parrot (Neophema chrysogaster)
Philippine Eagle (Pithecophaga jefferyi)
Po'ouli (Melamprosops phaeosoma)
Puerto Rican Parrot (Amazona vittata)
Raso Skylark (Alauda razae)
Red-cockaded Woodpecker (Picoides borealis)
Red-vented Cockatoo (Cacatua haematuropygia)
Ridgway's Hawk (Buteo ridgwayi)
São Tomé Grosbeak (Neospiza concolor)
Siberian Crane (Grus leucogeranus)
Slender-billed Curlew (Numenius tenuirostris)
Socorro Mockingbird (Mimodes graysoni)
Sociable Lapwing (Vanellus gregarius)
Spix's Macaw (Cyanopsitta spixii)
Sumatran Ground Cuckoo (Carpococcyx viridis)
Takahe (Porphyrio hochstetteri)
West Indian Whistling Duck (Dendrocygna arborea)
White-headed Duck (Oxyura leucocephala)
White-shouldered Ibis (Pseudibis davisoni)
Whooping Crane (Grus americana)
Writhed-billed Hornbill (Aceros waldeni)
Yellow-crested Cockatoo (Cacatua sulphurea)
Zino's Petrel (Pterodroma madeira)
[edit] Endangered reptiles
Loggerhead Sea TurtleAntigua Ground Lizard (Ameiva griswoldi)
Antigua Racer Snake (Alsophis antiguae)
Blunt-nosed Leopard Lizard (Gambelia silus)
Burmese Star Tortoise (Geochelone platynota)
Californian Walking Bird (Augusto squamish)
Coachella Valley Fringe-toed Lizard (Uma inornata)
Cuban Crocodile (Crocodylus rhombifer)
Flat Back Turtle (Natator depressa)
Grand Skink (Oligosoma grande)
Green Sea Turtle (Chelonia mydas)
Hawksbill Turtle (Eretmochelys imbricata)
Island Night Lizard (Xantusia riversiana)
Kemp's Ridley (Lepidochelys kempii)
Komodo Dragon (Varanus komodoensis)
Leatherback Sea Turtle (Dermochelys coriacea)
Loggerhead Sea Turtle (Caretta caretta)
Mesoamerican River Turtle (Dermatemys mawii)
Mona Ground Iguana (Cyclura stejnegeri)
Monito Gecko (Sphaerodactylus micropithecus)
Olive Ridley (Lepidochelys olivacea)
Otago Skink (Oligosoma otagense)
San Francisco garter snake (Thamnophis sirtalis tetrataenia)
Smith's Dwarf Chameleon (Bradypodion taeniabronchum)
St. Croix Ground Lizard (Ameiva polops)
[edit] Endangered amphibians
Santa Cruz Long-toed Salamander (photo courtesy of Don Roberson)Arroyo toad (Bufo californicus (=microscaphus))
Australian Lace-lid (Nyctimystes dayi)
Barton Springs Salamander (Eurycea sosorum)
Baw Baw Frog (Philoria frosti)
California Tiger Salamander (Ambystoma californiense)
Desert Slender Salamander (Batrachoseps aridus)
Fleischmann's Glass Frog (Hyalinobatrachium fleischmanni)
Houston toad (Bufo houstonensis)
Italian Spade-footed Toad (Pelobates fuscus insubricus)
Mississippi Gopher Frog (Rana capito sevosa)
Mountain Yellow-legged Frog (Rana muscosa)
Palmate Newt (Triturus helvetica)
Santa Cruz Long-toed Salamander (Ambystoma macrodactylum croceum)
Shenandoah Salamander (Plethodon shenandoah)
Sonoran Tiger Salamander (Ambystoma tigrinum stebbinsi)
Spotted Tree Frog (Litoria Spenceri)
Texas Blind Salamander (Eurycea rathbuni)
Wallum Sedge Frog (Litoria olongburensis)
Wyoming Toad ( Bufo baxteri (=hemiophrys))
[edit] Endangered fish
An Asian arowanaAsian arowana (Scleropages formosus)
Bonytail (Gila elegans)
Chinese paddlefish (Psephurus gladius)
Coelacanth (Coelacanthiformes)
Colorado pikeminnow (Ptychocheilus lucius)
Cui-ui (Chasmistes cujus)
Dwarf Pygmy Goby (Pandaka pygmae)
Gambusia eurystoma, native to Mexico, due to very limited habitat
Humpback chub (Gila cypha)
June sucker (Chasmistes liorus)
Moapa dace (Moapa coriacea)
Nassau grouper (Epinephelus striatus)
Virgin River chub (Gila seminuda)
[edit] Endangered arthropods
Alabama cave shrimp (Palaemonias alabamae)
Delhi Sands flower-loving fly (Rhaphiomidas terminatus abdominalis), due to severely limited range of habitat and development
Kentucky cave shrimp (Palaemonias ganteri)
San Bruno elfin butterfly (Incisalia mossii bayensis), due to limited range of habitat and development encroachment
Spruce-fir moss spider (Microhexura montivaga)
Tasmanian giant freshwater crayfish (Astacopsis gouldi)
Tooth cave spider (Neoleptoneta myopica)
White-clawed crayfish (Austropotamobius pallipes)
