奇特寄生虫让你胃口大好(双语有声)
作者：hahaleaf
来源：沪江论坛
2010-04-27 10:22
Invading Species Carrying Parasites Have Healthy Appetites
Invasive species can decrease biodiversity and drive resident species to the brink of extinction. But how do these interlopers fare so well in unfamiliar territory? One idea is that they’ve escaped their enemies, for example, the parasites that keep them in check on their home turf. But a study in the journal Biology Letters [Jaimie Dick et al., RRRl] suggests that notion doesn’t always stand up. Because at least one kind of invasive shrimp is an even bigger pest when it has a parasite on board.
外来物种入侵会减少生物多样性并可能致使当地物种灭绝。不过这些外来物种在完全陌生的环境当中怎么会这么为所欲为的呢？有人认为，陌生的环境中缺少这些外来物种的天敌，比如说抑制他们生长的寄生物。但《生物学快报》中一文则指出这一观点并非恒成立——至少有一种虾类，当被寄生物寄生时，生长不受抑制不说，危险系数还反而增加了。
The scientists were studying a freshwater shrimp commonly found in England. Fishermen brought the shrimp to Northern Ireland in the 1950s as a tasty treat for local trout. Well, the shrimp liked the new digs. So much that they’ve all but eliminated the native shrimp species. The strange thing is, they may have parasites to thank.
科学家们对一种英格兰常见的淡水虾进行了研究。20世纪50年代，渔民们把这些鳟鱼的美味佳肴带到了北爱尔兰，这些淡水虾倒是很乐意，不过土生土长的小虾可就大难临头了。但奇怪的是，在其中扮演微妙角色的竟是那些寄生生物。
In some streams, 70 percent of the invaders are infected with an intestinal worm that doesn’t go for the native shrimp. But this gut worm doesn’t slow them down. In fact, infected shrimp eat 30 percent more prey than those that are parasite-free.
在某些河流中，有70%的英格兰淡水虾被一种肠虫寄生，当地虾则未被寄生。而这些寄生虫不但没有抑制寄主们生长，反而让寄主们胃口大开，要比未被寄生多吃30%。
Which perhaps is not surprising. If you had a worm that constituted a quarter of your body weight, you’d eat more too.
这听起来可能没什么，不过想想看，要是也有条是你体重四分之一的蠕虫寄居在你体内的话，那你肯定也会大吃特吃的。
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