“在20世纪80年代，人们只是不认为青蛙正在消失。科学家表示，“不要惊慌，我们需要统计数据来证明这一点，所有人群都会随着时间的推移而自然波动”，等等，“澳大利亚詹姆斯库克大学的Lee Berger博士说。 “到1995年世界爬行动物大会[爬行动物和两栖动物的研究]时，研究人员不得不承认青蛙已经消失，他们找不到它们，他们不明白为什么它们已经消失或者到底是什么“危机早在20世纪70年代就开始了，当时青蛙从世界的河流，沼泽和森林中悄然消失，被新的阴险威胁所摧毁：Batrachochytrium dendrobatidis，一种对青蛙致命的致病真菌。也被称为“chytrid”，fugus慢慢地窒息青蛙，因为它损害了它的皮肤的正常功能。动物可在感染后一周内死亡。整个人口似乎在一夜之间消失。内华达大学（University of Nevada）助理教授杰米沃伊勒斯（Jamie Voyles）说：“看到这种疾病在15年前实时传播是令人震惊的。” “在巴拿马，热带雨林中的斑点在两栖动物的呼唤声中震耳欲聋。他们的丰富是令人难以置信的;你甚至无法走过森林而不必担心踩到它们。第二年夏天，他们刚刚离开。“正如鸟鸣声的消失让科学家们注意到杀虫剂对蛋壳的破坏性影响一样，雨林中令人毛骨悚然的安静告诉生物学家有些不对劲。最有名的伤亡：哥斯达黎加的金蟾蜍（Incilius periglenes），尚未自1989年以来澳大利亚的壮观奇特的胃育雏青蛙（Rheobatrachus），其中孕育幼蛙在他们的胃看到的，也不见了。很难确定有多少种食物已经灭绝，但是最近的一项研究估计200种青蛙已经被真菌消灭了。现在许多人在受到这种疾病的摧毁之后只是坚持下去，这种疾病已经影响了全世界的700种。 “老年人说澳大利亚的山脉曾经对Corroboree青蛙的叫声产生了积极的喧嚣 – 他们是如此丰富的人们用它们作为鱼饵。现在野外不到100只，“伯杰说。今天，其余的青蛙被隔离在30平方米的室外围栏中，由3米高的金属围栏保护。 “这不是一个理想的解决方案，但它取得了成功，”她说。她的诊断不能掉以轻心。 Berger从一开始就研究了chytrid;她是该真菌的共同发现者之一，她作为博士论文的一部分进行了跟踪，并于1998年在PNAS期刊中进行了描述。据信，非洲爪蛙非洲爪蟾的国际贸易 – 广泛用作妊娠试验。 20世纪50年代和60年代 – 将真菌释放到野外。由于非洲两栖动物与它们的原生栖息地中的真菌共存，因此它们对它有一定的抵抗力。但其他两栖动物并不那么幸运。
加拿大卡尔加里大学生物学Essay代写:孕测对青蛙带来的灾难
“In the 1980s, people just didn’t think frogs were disappearing. Scientists said ‘don’t panic, we need the stats to prove it, all populations have natural fluctuations over time,’ and so on,” says Dr Lee Berger of James Cook University in Australia. “By the time of the World Congress of Herpetology [the study of reptiles and amphibians] in 1990, researchers had to admit that the frogs had disappeared, they couldn’t find them and they didn’t understand why they had vanished or what to do.” The crisis had started as early as the 1970s, when frogs began to quietly vanish from the rivers, marshes and forests of the world, taken down by a new and insidious menace: Batrachochytrium dendrobatidis, a pathogenic fungus that is lethal to frogs. Also known as “chytrid”, the fugus slowly suffocates the frog as it impairs the normal functioning of its skin. Animals can die within a week of infection. Entire populations seem to vanish overnight. “It was shocking to watch the spread of the disease happen in real time 15 years ago,” says Jamie Voyles, assistant professor at the University of Nevada. “In Panama, spots in the rainforest were deafeningly loud with amphibian calls. Their abundance was incredible; you couldn’t even walk through the forest without worrying about stepping on them. The next summer they were just gone.” Just as the disappearance of birdsong alerted scientists to the devastating impacts of pesticides on eggshells, the eerie quiet of the rainforest told biologists something was wrong. The most famous casualty: the Costa Rican golden toad (Incilius periglenes), which has not been seen since 1989. Australia’s spectacularly quirky gastric-brooding frogs (Rheobatrachus), which gestated froglets in their stomachs, are also gone. It’s hard to know for sure how many species chytrid has consigned to extinction, but a recent study estimates 200 species of frog have been wiped out by the fungus. Many now are just hanging on after being decimated by the disease, which as has affected 700 species worldwide. “Older people say the Australian mountains used to be positively noisy with the calls of the Corroboree frog – they were so abundant people used them as fishing bait. Now there are less than 100 in the wild,” says Berger. Today, the remaining frogs have been sequestered in a 30 sq m outdoor enclosure, protected by a 3m-high metal fence. “It’s not an ideal solution, but it has been a success,” she says. Her diagnosis is not to be taken lightly. Berger has studied chytrid since the beginning; she is one of the co-discoverers of the fungus, which she tracked as part of her PhD thesis and described in the journal PNAS in 1998. It is believed the international trade in the African clawed frog Xenopus laevis – widely used as pregnancy tests in the 1950s and ‘60s – released the fungus into the wild. As the African amphibians co-existed with the fungus in their native habitats they had some resistance to it. But other amphibians were not so lucky.