NSF 今日图说 | 蜘蛛是怎么在夏威夷进化的（欢迎打卡）

本文转自 https://news.science360.gov/

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大约两三百万年前，一群来路不明的蜘蛛向风中吐出了长长的丝线，启航穿越了太平洋，来到了夏威夷。好吧，这只是拟人的描述。这些蜘蛛最先只是其他蜘蛛的寄生虫，它们侵占了寄主的丝网，切断丝线，偷走了那些被抓住的昆虫。当它们刚到达夏威夷时，并没有多少蜘蛛网可以偷盗。所以，它们开发了新技能，找到了其他幸存下来的方法——捕捉并吃掉其他的蜘蛛。慢慢地，进化出了一个可以生活在岩石上的新品种，之后又有了一个可以生活在树叶下的新品种。新品种就这样一个个多了起来，总共有 11 个。查尔斯·达尔文首先在观察加拉帕戈斯群岛雀类的喙时，注意到了同类的现象，将其称之为“自适应辐射”。他对雀的多样性的研究，引导他发现了自然选择进化论。但时至今日，关于自适应辐射以及随之而来的进化究竟是怎样产生的，背后的原理又是什么，仍然有许多未知之处。夏威夷因为相对孤立，比加拉帕戈斯群岛更适合生物多样性的发展。

How brightly colored spiders evolved on Hawaii again and again

About 2 to 3 million years ago, a group of spiders from parts unknown let out long silk threads into the wind and set sail, so to speak, across the Pacific Ocean to Hawaii. These spiders were parasites of other spiders, invading their webs and snipping threads to steal insects that had been caught. But there weren't many webs to rob on Hawaii when they arrived. So they expanded their repertoire, looking for other ways to survive by trapping and eating other spiders. A new species evolved from those first spiders, after finding a way to live on rocks. And then another species evolved to live under leaves. And then another. And then 11 more species. Charles Darwin first noted this phenomenon, called adaptive radiation, in the beaks of finches of the Galapagos Islands. His study of the finches' diversity led to his theory of evolution by natural selection. Yet today, much remains unknown about how adaptive radiation, and thus evolution, actually work. Hawaii is even more of a hotbed for biological diversification than the Galapagos due to its isolation.

Image credit: George Roderick