英语听力：自然百科 老乌龟传宗接代不容易（在线收听） |
Hopes are fading that lonesome George, a unique giant Galápagos tortoise, will become a father. George lives in the Galápagos National Park in Ecuador and is believed to be the last living member of its species. Conservationists are anxious to ensure his blood line continues, but it seems George is not yet destined to become a father. Park officials introduced George to two eligible female companions but the remaining eight eggs laid by the giant tortoises are infertile. Unfortunately, we opened each one of them and to look, to see if we could find a sign of an embryo. And, none of them had a sign of any embryo development, which suggests that the eggs were not fertile.
Some of Caccone's work has been partially funded by National Geographic. Though the eggs were not fertilized, there was a small glimmer of hope as it was the first time any of George's mates were able to produce eggs. Park rangers have been trying for 36 years to coax George into fathering babies.
George could be sterile, although the eggs could also have been deficient since the females have not laid eggs for 15 years. The tortoises may have adjusted poorly to captivity which could have left him infertile. All the diet in the breeding center could have had a negative impact on their reproductive systems.
Either way, conservationists are not giving up just yet. A team of biologists and park rangers have been taking blood samples from tortoises on nearby Isabella Island and in search of hybrid species that share as many or more genes with lonesome George. George, first discovered in 1971 was taken to a breeding center on Santa Cruz Island in 1972. He's become a major conservation icon, and tourist attraction in the Galápagos Islands. |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2008/255319.html |