托福阅读素材：白犀保护希望渺茫(自然科学篇)

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　　当北方白犀牛只剩下了一头雄性，该如何去保护?人类为了拯救这一物种，想到了那些方法，又做了哪些尝试呢?今天的托福阅读材料就是有关于白犀牛保护的，一起学习吧!

　　疑难词：

　　in the pen关在栏中

　　ranger n. 突击队员;漫游者;骑警

　　poaching vt.偷猎;窃取vi. 偷猎;侵犯;剽窃

　　degenerate n. 堕落的人adj. 退化的;堕落的vi. 退化;堕落

　　enclosure n. 附件;围墙;围场

　　trim. n. 修剪;整齐;情形vt. 修剪

　　artificial adj. 人造的;仿造的

　　vitro fertilization 体外受精

　　hybrid n. 杂种，混血儿;混合物adj. 混合的;杂种的

　　mate vi. 交配

　　expectancy n. 期望，期待

　　diminishes减少，缩小

　　futile adj. 无用的;无效的

　　With last male on earth, hope for saving rare white rhino dim

　　唯一雄性白犀幸存，稀少白犀的保护希望渺茫

　　In central Kenya's Ol Pejeta Conservancy, Sudan lies quietly in his pen, alone and lonely. Outside, there is a team of armed rangerswho take turns guarding the mammal day and night.

　　Sudan is the last male of five remaining known northern white rhinos in the world.

　　NATURAL BREEDING ATTEMPTS FAIL

　　失败的自然繁殖尝试

　　As its name suggests, the rare species was first captured in 1980s in Sudan, which, together with DR Congo and Central African Republic, used to be their natural habitat. However, years of poaching for rhino horns as well as conflicts in the region have resulted in the animal's disappearance from the wild almost a decade ago.

　　Sudan had then been kept at a zoo in Czech Republic before brought to the Kenyan conservancy in 2009 with another male, Suni, and two females, in a hope that the natural conditions here can provide "the last chance of survival" and help them breed.

　　Unfortunately, Suni died last October, which was followed by the death of another male in a U.S. Zoo in December, bringing down the number of remaining northern white rhinos on the planet from seven to five: Sudan and two females in Ol Pejeta, and another two females living separately in zoos of the United States and Czech Republic.

　　At 42, Sudan is too old to mate as the mammal usually has a life expectancy of 40 years in wild, and maybe a little longer in captivity. The rest four females are also barely to reproduce either because of old age or other physical reasons.

　　"It's highly unlikely that the animal will not go extinct," said Richard Vigne, Ol Pejeta's chief executive. "If a species diminishes to such small number, then it becomes very difficult to recover that species."

　　Vigne said there were several natural breeding attempts when the animals were first brought to the conservancy, but all failed.

　　"The animals haven't lived in a natural environment for a long time, and they are getting old and inter-related," said Vigne, adding that if the rhinos haven't bred for a long time, it would not be easy for them to start again as their reproductive organs may start to degenerate.

　　Mohammed Doyo, the keeper of the rare species, also recalled he saw Sudan try to mate three years ago with a female southern white rhino, yet it eventually turned out futile.

　　Like the northern white rhino, a southern white one is a subspecies closely related to the northern, but is less endangered. It has an estimated population of 20,000 worldwide, mostly in South Africa.

　　Both subspecies has wide month though the northern has hair along the edge of its ears. Moreover, the northern tends to be slightly less social than the southern, and prefers thicker bush while the southern likes to be in open space.

　　ARTIFICIAL REPRODUCTION METHODS DIM

　　人工繁殖希望不大

　　In this 90,000 acre of conservancy, instead of wandering around on the vast savanna as before, Sudan now has been kept in enclosure for a year to avoid hurt from other rhinos, according to Doyo. Though guarded by armed rangers around the clock, the mammal's horns had also been trimmed for fear of poaching.

　　"He is like my own children. I would feel very sad if we lose it," said Doyo.

　　"Sudan could die tomorrow," said Vigne, noting that the last hope to save the rare species from complete distinction would be artificial reproduction methods.

　　One way is vitro fertilization: take eggs and sperms of northern white rhinos and create an embryo, which is then implanted into a female southern white rhino, hoping to get a northern white calf.

　　"However, this technology has never been done in rhinos before, and it is very expensive," said Vigne, adding that they would first develop the technique on southern white rhinos, and apply it on the northern white rhinos once there is enough money and the technique gets perfected.

　　"We need to raise money first, and we estimate it would take as long as two years before we can get a successful pregnancy with a pure northern rhino embryo," he said.

　　There is also another option, which will use some already stored semen of northern white rhinos in the world and crossbreed it with female southern white rhinos to get a hybrid. However, this means, if succeeds, it would not be a pure northern white rhino.

　　"It is not perfect, but it is better than nothing," Vigne lamented(lament，v. 哀悼;悲叹;悔恨), calling on more efforts to save the rare rhino and other endangered wildlife.

　　"Poaching of rhinos across Africa still continues at a very high rate. If we as human race don't do something to stop it, what is happening now to the northern white rhino will happen to many other species," he said.