時差N小時:人類,家鼠與他們的棲息地

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?

雅艾爾：我們經(jīng)常聽說人們的行為，人類的擴張會如何危害到野生棲息地。但是你能想到一些動物，它們的生存會因人類的消失而受到威脅?

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

唐：那肯定是依靠人類獲得食物和庇護所的動物。老鼠包括在內(nèi)嗎?

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

雅艾爾：你的思路很對。我想到了家鼠。你聽說過滅絕的圣基爾達家鼠的故事嗎?

Don: No.

唐：沒有。

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.

雅艾爾：圣基爾達是一座距離蘇格蘭西海岸100英里的小島群。人類在這片孤獨的群島上棲息生活了兩千多年(從銅器時代到1930年)。在1930年，僅存的為數(shù)很少的圣基爾達居民也因疾病，糧荒和一戰(zhàn)傷亡，被迫永久地遷離家園?？茖W(xué)家們認為早在公元500年，古代北歐人就來到圣基爾達，同時帶來一些不請自來的偷渡者——歐洲家鼠。因為長期與大陸隔離，這群老鼠進化成獨特的物種，它們的個頭比祖先更大，體型也變得不同。圣基爾達也是一類特殊田鼠的故鄉(xiāng)，它們也可能是偷渡過來，經(jīng)過進化成為新的物種。然而，圣基爾達的家鼠需要溫暖的住所，農(nóng)田還有它們的人類鄰居掉落的食物屑而生存。居民搬遷后的三年里，圣基爾達家鼠全部滅絕。相反，田鼠卻幸存下來，至今仍生活在圣基爾達島上。

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

唐：這是因為它們不依靠人類獲取食物和住所嗎?

Yael: Exactly.

雅艾爾：正是這樣。

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

唐：哇，多么引人入勝的行為進化案例啊!