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Safe dragonfly larvae that could sense the presence of their predators had a higher mortality rate than unstressed larvae. Christopher Intagliata reports
Christopher Intagliata報(bào)道稱，蜻蜓幼蟲(chóng)可以感知捕食者的存在，雖然這使它們更加安全，但卻使它們的死亡率高于一般未感受到壓力的幼蟲(chóng)。
A hungry fish can kill prey with a quick bite. That is, of course, if its prey hasn't already died of fright. Take tasty dragonflies. The mere presence of predators—even caged ones—is enough to scare dragonflies to death, according to a study in the journal Ecology.
一條饑餓的魚(yú)能夠一口咬死其獵物。當(dāng)然，前提是經(jīng)過(guò)一番殊死搏斗之后獵物依然健在。以有趣的蜻蜓為例，根據(jù)《生物學(xué)》雜志的一篇研究報(bào)告，捕食者的出現(xiàn)能夠?qū)Ⅱ唑褔標(biāo)溃呐逻@些捕食者被關(guān)在籠子里面。
Researchers collected wild dragonfly larvae, and placed them in tanks with fish or insect predators. The larvae could see and smell their hunters—but were kept safe by underwater cages. After two months, the researchers took a head count—and found that dragonfly larvae sharing quarters with their killers were two to four times as likely to die off, compared to counterparts living in predator-free waters. And they had slimmer chances of surviving metamorphosis, too.
研究者將野生蜻蜓幼蟲(chóng)放進(jìn)裝有魚(yú)類或昆蟲(chóng)類捕食者的容器中，具體的安放位置是在水下的籠子里，這里有絕對(duì)的安全保障，但同時(shí)幼蟲(chóng)們也能夠看見(jiàn)并嗅到它們的天敵。兩個(gè)月之后，研究者發(fā)現(xiàn)，與捕食者同住的蜻蜓幼蟲(chóng)死亡率是正常蜻蜓幼蟲(chóng)的2-4倍。而且它們蛻變的存活率也更低。
The authors suggest a couple reasons why. First, prey tend to make fewer forays for snacks when predators are lurking around, so they may not be as nutritionally fit. And previous studies have shown that the presence of predators ups stress levels in prey, weakening their immune systems and making them more vulnerable to disease—and death.
文章的作者提出了幾點(diǎn)原因。首先，當(dāng)有捕食者在場(chǎng)時(shí)，處于劣勢(shì)的被捕食者會(huì)減少覓食行為，所以它們的營(yíng)養(yǎng)狀況不佳。加上之前的研究表明，捕食者的出現(xiàn)使被捕食者的壓力水平升高，降低了它們的免疫系統(tǒng)機(jī)能，使它們更易生病乃至于死亡。
As if being eaten wasn't enough to worry about, looks can kill too.
正所謂：死不足懼，怕死堪憂。看來(lái)生物界的規(guī)律是相通的。
