您现在的位置: 纽约时报中英文网 >> 纽约时报中英文版 >> 科学 >> 正文

迭戈,让族群免于灭绝的“超级”象龟

更新时间:2017-3-15 11:44:58 来源:纽约时报中文网 作者:佚名

Meet Diego, the Centenarian Whose Sex Drive Saved His Species
迭戈,让族群免于灭绝的“超级”象龟

CHARLES DARWIN RESEARCH STATION, Galápagos — Of all the giant tortoises on these islands, where the theory of evolution was born, only a few have received names that stuck.

加拉帕戈斯查尔斯·达尔文研究站(Charles Darwin Research Station)——这些小岛是进化论诞生之地,岛上的巨大象龟当中,只有少数几只拥有被人们叫开的名字。

There was Popeye, adopted by sailors at an Ecuadorean naval base. There was Lonesome George, last of his line, who spent years shunning the females with whom he shared a pen.

已经去世的一只是被厄瓜多尔某海军基地的水手收养过的卜派(Popeye)。另一只叫孤独乔治(Lonesome George),是其所属亚种最后的血脉,曾在很多年时间里躲避跟自己同住一个屋檐下的雌性象龟。

And there is Diego, an ancient male who is quite the opposite of George.

活着的有迭戈(Diego),一只与乔治截然相反的年长雄性象龟。

Diego has fathered hundreds of progeny — 350 by conservative counts, some 800 by more imaginative estimates. Whatever the figure, it is welcome news for his species, Chelonoidis hoodensis, which was stumbling toward extinction in the 1970s. Barely more than a dozen of his kin were left then, most of them female.

迭戈繁殖了数百只后代——保守估计有350只,乐观估计约为800只。不论数字是多少,对他所属的亚种、在1970年代几近灭绝的艾斯潘诺拉岛加拉帕戈斯象龟来说都是好消息。当时,他的同类只剩下十几只,其中大多是雌性。

Then came Diego, returned to the Galápagos in 1977 from the San Diego Zoo.

然后迭戈横空出世,于1977年从圣地亚哥动物园(San Diego Zoo)重返加拉帕戈斯。

“He’ll keep reproducing until death,” said Freddy Villalva, who watches over Diego and many of his descendants at a breeding center at this research facility, situated on a rocky volcanic shoreline. The tortoises typically live more than 100 years.

“他会一直繁衍后代,直到死亡来临,”在这个研究站的一个繁殖中心里看顾迭戈及其很多后代的弗雷迪·维拉尔瓦(Freddy Villalva)说。研究站位于布满岩石的火山海岸线上。这些象龟通常能活到100多岁。

The tales of Diego and George demonstrate just how much the Galápagos — a province of Ecuador — have served as the world’s laboratory of evolution. So often here, the fate of an entire species, evolved over millions of years, can hinge on whether just one or two individual animals survive from one day to the next.

迭戈和乔治的故事表明,加拉帕戈斯虽然只是厄瓜多尔的一个省份,却在很大程度上充当着全世界的进化实验室。这里常常出现的情况是:某个经过千百万年进化而来的物种的命运,全然取决于一两只动物能否日复一日地活下去。

Diego, and his offspring, are part of one of the most high-profile efforts to keep Galápagos tortoise populations thriving. The tortoise, estimated to be perhaps a century old, is one of the main drivers of a remarkable recovery of the hoodensis species — now more than 1,000 strong on their native island of Española, one of the dozen Galápagos islands.

迭戈及其后代,是旨在让加拉帕戈斯象龟族群欣欣向荣的一项备受瞩目的努力的组成部分。这只象龟据估计可能已有百岁高龄,是其所属象龟亚种实现不可思议的复兴的主要驱动力之一——目前,超过1000只加拉帕戈斯象龟在其原生栖息地艾斯潘诺拉岛上茁壮生长着。艾斯潘诺拉岛和其他十几个岛屿一起构成了加拉帕戈斯群岛。

His story stands in contrast to Lonesome George, who was perhaps the most famous Galápagos resident when he died in 2012, at about 100 years old. His species, Chelonoidis abingdonii, now lives only on T-shirts and postcards because George, found in 1971 by a snail biologist on the island of Pinta, never produced any offspring in captivity.

迭戈的故事与孤独乔治的故事形成了鲜明的对比。年纪约为100岁的孤独乔治在2012年死去时,可能是加拉帕戈斯最有名的居民。他所属的亚种——平塔岛象龟,目前只存在于T恤衫和明信片上,因为被一名研究蜗牛的生物学家于1971年在平塔岛上发现的乔治,被圈养后从未繁殖过任何后代。

An estimated 11 of about 115 known animal species have gone extinct since scientists began keeping records on the Galápagos. But the establishment of a national park, and the efforts of scientists, mean that extinctions are now a rarity. Which is why the death of George was such a blow.

据估计,自从科学家开始建立关于加拉帕戈斯的记录以来,约115个已知动物物种当中有11个已经灭绝。但由于当局开办了一个国家公园,科学家们也在进行种种努力,现如今,物种灭绝已鲜有发生。正因为如此,乔治之死才会成为非常沉重的打击。

Scientists did all they could to coax more abingdonii out of George and his mates. Only when George had died did an autopsy reveal it wasn’t lack of potency that impeded his reproduction, but a more anatomical ailment affecting his reproductive organ.

科学家曾竭尽所能地撮合乔治和他的交配对象,想让他们繁殖出更多平塔岛象龟。但直到乔治死去时,人们通过尸体解剖才发现,妨碍其繁衍后代的并不是活力的匮乏,而是让其生殖器官受到影响的一种与身体结构更为相关的疾病。

“We don’t like to talk about it,” said James P. Gibbs, a professor of vertebrate conservation biology at the State University of New York College of Environmental Science and Forestry in Syracuse, and one of the world’s experts on the tortoises, only half joking.

“我们不愿意谈论这个,”纽约州立大学环境科学与林业科学学院(State University of New York College of Environmental Science and Forestry in Syracuse)脊椎动物保育生物学教授、象龟研究权威詹姆斯·P·吉布斯(James P. Gibbs)半开玩笑地说。

Dr. Gibbs had returned to the Galápagos that week from upstate New York to bring the stuffed remains of George and several expensive air-conditioning units and UV filters that would preserve the reptile in perpetuity in a mausoleum of sorts on one of the islands.

那一周,吉布斯从纽约州北部返回加拉帕戈斯,带回了乔治已被制成标本的遗骸,还有好几台昂贵的空调机组和紫外线滤波器,可以用来在其中一座岛屿上建造一个类似陵墓的地方,将这只爬行动物永久地保存起来。

Both George and Diego had shells much smaller than many other species, and long necks to reach the few cactuses growing on their wind-swept island. In a way, those small shells were a curse on both their houses: Abingdonii and hoodensis were easy prey for the buccaneers and whalers who poured onto their islands in previous centuries and saw only defenseless, slow-moving meals that could easily be carted away.

乔治和迭戈都有比其他许多亚种小得多的龟壳,还有长长的脖子,可以触及它们所在狂风肆虐的岛屿上生长的为数不多的仙人掌。从某种程度上讲,这种小龟壳对这两个亚种而言都是一种诅咒:平塔岛象龟和艾斯潘诺拉岛象龟很容易被海盗和捕鲸人捕获,这些人在前几个世纪大批来到它们所在的岛屿,结果只看到这种没有防御能力、行动缓慢而且可以轻松运走的“食物”。

Nor did it help that the giant tortoises of the Galápagos can survive for up to a year in the hull of a ship, meaning they provided a near-endless supply of fresh meat as they were stacked below decks by the hundreds. They were even tossed overboard when a ship needed to lose ballast for a quick getaway.

加拉帕戈斯的巨型象龟可以在船舱中存活一年,这种能力也没起到好作用,因为这意味着把它们成百上千地叠放在船只的甲板下,就可以获得几乎取之不尽的鲜肉供应。而当一艘船需要减轻重量好迅速溜走时,这些陆龟又会被抛下船。

Among those who dined on giant tortoise flesh: Charles Darwin.

食用过这种巨型象龟肉的人包括:查尔斯·达尔文(Charles Darwin)。

“We lived entirely on tortoise meat, the breastplate roasted … with flesh on it, is very good; and the young tortoises make excellent soup,” Darwin wrote in 1839, near the peak of the tortoise plunder in which some 200,000 were killed or carried away from the islands.

“我们完全依靠龟来获取肉食,”把龟的腹甲在火上烤一烤……连着肉一块,味道很不错;幼龟可以熬成美味的龟汤,”达尔文在1839年写道,时间接近这些象龟遭劫掠的高峰时期——当时有20万只象龟被杀或被带离群岛。

In the end, finches led him to the theory of evolution, not tortoises.

到最后,却是雀科鸣禽让达尔文发现了进化论,而不是象龟。

“He may have eaten his best specimens,” Dr. Gibbs said.

“他或许把自己的最佳样本给吃掉了,”吉布斯说。

The recovery of Diego’s hoodensis species also brings up a quandary, one that perplexed Darwin during his adventures in the Galápagos more than a century ago, when he studied the fauna.

迭戈所属的亚种艾斯潘诺拉岛象龟的复兴也带来了一种让人左右为难的窘境——当达尔文于一个多世纪之前在加拉帕戈斯探险、研究动物群时,也曾被这个问题难住。

As Diego produces more offspring, and as those he has produced reproduce with one another, the entire hoodensis species could begin to look like Diego.

随着迭戈繁殖出更多后代,随着他的后代相互交配繁殖,整个艾斯潘诺拉岛象龟亚种可能会开始长得和迭戈一样。

Evolutionary scientists call this process the bottleneck effect — when survivors’ genes come to dominate the gene pool as populations rebound. It’s particularly true on islands like Española, where tortoises from other lines will not breed with Diego’s kin.

进化科学家称这个过程为瓶颈效应——在种群数量回升之时,幸存者的基因开始主导整个基因库。在诸如艾斯潘诺拉岛这样的岛屿上,情况尤其如此。在那里,其他亚种的象龟不会与迭戈那个亚种繁殖后代。

Tortoise experts were divided on what risk that presents for hoodensis on a recent afternoon. Dr. Gibbs called it a “dangerous zone,” where little genetic diversity could mean susceptibility to a dangerous disease or changes in habitat because of climate change.

在最近的一个下午,象龟专家们就这会给艾斯潘诺拉岛象龟造成什么危险产生了分歧。吉布斯称之为“危险地带”,因为基因多样性太少可能意味着容易遭受某种危险疾病或气候变化引起的环境变化的影响。

But Linda Cayot of the Galápagos Conservancy dissented, saying island species on the Galápagos have a long history of being decimated to just a few survivors that rebounded without incident — like a population of giant tortoises that chose to live in the caldera of a volcano. After the volcano exploded 100,000 years ago, the tortoises bounced back and returned to the caldera.

但加拉帕戈斯自然资源管理委员会(Galápagos Conservancy)的琳达·卡约(Linda Cayot)表示异议,称加拉帕戈斯的海岛物种有着被大批毁灭至只有少数存活、之后又平安无事地实现数量回升的悠久历史——比如一群选择生活在一座火山的破火山口的巨型象龟。在这座火山于10万年前爆发之后,这些象龟的数量逐渐回升,而且返回了破火山口。

“Every species came from a bottleneck,” Dr. Cayot said. “It’s what happens in the Galápagos.”

“每个物种都是绝处逢生,”卡约说。“在加拉帕戈斯,情况就是这样。”

“全文请访问纽约时报中文网,本文发表于纽约时报中文网(http://cn.nytimes.com),版权归纽约时报公司所有。任何单位及个人未经许可,不得擅自转载或翻译。订阅纽约时报中文网新闻电邮:http://nytcn.me/subscription/”

相关文章列表