时差N小时:人类,家鼠与他们的栖息地

Yael: We often hear about how human activity andexpansion can endanger wildlife habitats. But canyou think of any animals that might be threatenedby the disappearance of humans?

雅艾尔：我们经常听说人们的行为，人类的扩张会如何危害到野生栖息地。但是你能想到一些动物，它们的生存会因人类的消失而受到威胁?

Don: It must be something that depends on humansfor food or shelter. What about rats?

唐：那肯定是依靠人类获得食物和庇护所的动物。老鼠包括在内吗?

Yael: You're on the right track. I was thinking of house mice. Have you heard the story of theextinct St. Kilda House Mouse?

雅艾尔：你的思路很对。我想到了家鼠。你听说过灭绝的圣基尔达家鼠的故事吗?

Don: No.

唐：没有。

Yael: St. Kilda is a small group of islands about one-hundred miles off the west coast ofScotland. The isolated archipelago was inhabited by humans for more than two thousandyears, from the Bronze Age until 1930. In 1930 the few remaining residents of St. Kilda werepermanently evacuated because of sickness, crop failure and casualties of World War I.Scientists believe that as early as 500 BC, Norse settlers arrived in St. Kilda and brought alonga few unwanted stowaways—European house mice. Isolated from their mainland relatives,these house mice evolved over time into a distinct species, larger and shaped differently fromtheir ancestors. St. Kilda is also home to a unique subspecies of field mouse, that probably alsoarrived as stowaways and evolved into a new species. But the St. Kilda house mouse neededthe warm houses, farms and dropped food crumbs of its human neighbors to survive. Withinthree years of the humans evacuating, all the St. Kilda house mice had died off. In contrast,the field mice survived and are still living on St. Kilda today.

雅艾尔：圣基尔达是一座距离苏格兰西海岸100英里的小岛群。人类在这片孤独的群岛上栖息生活了两千多年(从铜器时代到1930年)。在1930年，仅存的为数很少的圣基尔达居民也因疾病，粮荒和一战伤亡，被迫永久地迁离家园。科学家们认为早在公元500年，古代北欧人就来到圣基尔达，同时带来一些不请自来的偷渡者——欧洲家鼠。因为长期与大陆隔离，这群老鼠进化成独特的物种，它们的个头比祖先更大，体型也变得不同。圣基尔达也是一类特殊田鼠的故乡，它们也可能是偷渡过来，经过进化成为新的物种。然而，圣基尔达的家鼠需要温暖的住所，农田还有它们的人类邻居掉落的食物屑而生存。居民搬迁后的三年里，圣基尔达家鼠全部灭绝。相反，田鼠却幸存下来，至今仍生活在圣基尔达岛上。

Don: Is that because they didn't depend on humans for food or shelter?

唐：这是因为它们不依靠人类获取食物和住所吗?

Yael: Exactly.

雅艾尔：正是这样。

Don: Wow. What a fascinating example of evolution in action!

唐：哇，多么引人入胜的行为进化案例啊!