经济学人71:动物行为 欲壑难填

 　　Science and Technology Animal behaviour Sexual appetite

　　科技 动物行为 欲壑难填
　　Being a male spider is even more dangerous than previously 1 thought
　　雄性蜘蛛遭遇的险境远远超乎人们之前的想象
　　FOR male spiders, the equivalent of a post-coital cigarette is not a sensible option.
　　对于雄性蜘蛛而言，交配过后悠闲地吸上一口美烟可不是什么明智的选择。
　　Making straight for the door is much wiser, since he who hangs around risks being eaten by his consort 2.
　　拍拍屁股直接走人才是更为聪明的做法，因为自己随时可能成为性伴侣的口食。
　　In this context, the females of Leucauge argyra, a Central American species, are particularly fiendish.
　　中美洲有种雌性长角银腹蛛，其凶残至极的个性就是上述情况的最好体现。
　　They seem to have subverted 3 a male trick that is intended to ensure paternity rights, and turned it into a trap.
　　她们似乎在颠覆雄性蜘蛛欲掌父权而惯用的伎俩并将这种伎俩变成温柔的陷阱。
　　Many animals—not just spiders—make plugs of mucus to seal the female's orifice after mating.
　　包括蜘蛛在内的许多动物都会制作一种封堵粘液，以便交配之后将雌性伴侣的生殖管道封闭。
　　Normally such plugs are secreted 4 by the male, to stymie 5 subsequent suitors.
　　通常情况下，这种粘液由雄性分泌，以此阻断其它狂蜂浪碟的追求欲念。
　　In spiders, though, the female sometimes assists the process.
　　但就蜘蛛而言，雌性蜘蛛有时也会协助这个过程。
　　At first sight, that is odd.
　　乍看上去，这是种奇怪的现象。
　　It is always in a male's interest to try to stop a female mating again.
　　试图阻止雌性蜘蛛再次交配通常是对雄性蜘蛛有利的事情。
　　Contrariwise, that female might come across a better male and thus wish to be rid of the first lot of sperm 6. (Female spiders can do this because they store sperm for a period of days or weeks before they use it to fertilise their eggs.)
　　但反过来看，雌性蜘蛛也可能会遇到更好的雄性伴侣，因此就会打算抛弃前夫的精液（雌性蜘蛛之所以能这样做是因为她们能将精液存留数日或几周的时间，然后决定是否用其对卵子受精）。
　　After studying this phenomenon for several years, Anita Aisenberg of the Clemente Estable Institute of Biological Research in Uruguay has concluded that females are able to assess a male's quality during mating and that they assist plug formation only when a mate passes muster 7 and they thus wish to give his sperm priority.
　　乌拉圭Clemente Estable生物研究所的Anita Aisenberg对此现象潜心研究几年后得出结论，雌性蜘蛛在交配过程中能够评估雄性蜘蛛的质素，只有被雌性蜘蛛认可了的雄性蜘蛛才可能协助他封堵自己的生殖管道并优先采用其精液受孕。
　　Which makes sense.
　　这种解释是有道理的。
　　In a paper just published in Naturwissenschaften, though, Dr Aisenberg and her colleague Gilbert Barrantes at the University of Costa Rica report that female Leucauge argyra go further: they create plugs all by themselves.
　　但Aisenberg博士与她的哥斯达黎加大学同事Gilbert Barrantes在《自然科学》杂志上新发表的论文指出："长角银腹"雌性蜘蛛还有一手更绝妙的高招：她们能自行分泌封堵粘液。
　　And that really is odd.
　　这就真的让人觉得奇怪了。
　　Because plugging is in a male's interest, he should never leave it just to the female.
　　因为封堵行为是对雄性蜘蛛有利的事情，他怎么会将这种特权拱手让给雌性蜘蛛单独完成呢？
　　Except that in this case the plug turns out to be very much not in a male's interest.
　　除非有这种情况出现，即封堵行为会对雄性蜘蛛有非常不利的影响。
　　In fact, it can kill him.
　　事实上，这种让权造就了雄性蜘蛛的死亡。
　　Spider sex is unusual in that males transfer their sperm to the female on small limbs called pedipalps.
　　蜘蛛的交配方式与众不同，雄性蜘蛛利用称做"须肢"的小肢干将精液输送给雌性蜘蛛。
　　They use these to pick their sperm up from their genitals and insert it into the female's sexual orifice, rather than copulating directly.
　　雄性蜘蛛先用"须肢"将精液从生殖器中取出再将其插入到雌性蜘蛛的性器官内，而不是采用直接交配方式。
　　Dr Aisenberg and Dr Barrantes observed the process 17 times in pairs of Leucauge argyra.
　　isenberg博士和Barrantes博士观察了17对长角银腹蛛的交配过程。
　　On the 14 occasions a sexual plug was made, the female produced it without assistance from the male.
　　A在14例交配过程中，雌性蜘蛛在未借助雄性蜘蛛帮助的情况下自己了分泌封闭粘液。
　　On ten of these occasions the male's pedipalps then seemed to get stuck while he was transferring the sperm (which is rarely the case in other species of spider), and he had great difficulty freeing
　　这14例交配中出现10例雄性蜘蛛在输送精液时，"须肢"似乎被卡在了雌性蜘蛛的性器官内（此情况在其它种类蜘蛛身上极少发生），使他难以挣脱。
　　In two of those ten instances, he was eaten as a result.
　　10例中有2例以雄性蜘蛛被吃掉而告终。
　　The two researchers conclude, therefore, that what was once a mechanism 8 which allowed females to discriminate 9 between males has evolved into a way of trapping them so that they can be consumed at leisure.
　　因此两位研究人员得出结论，雌性蜘蛛过去用来判别雄性蜘蛛质素的机制已经演化成"诱骗"他们的手段，并从容地吃掉被诱骗的雄性蜘蛛。
　　Whether only high-quality males, whose sperm the female also wishes to keep, are affected 10 is not yet clear—though eating such males may bring the bonus of denying their sperm to rivals.
　　是否只有高质素的雄性蜘蛛（雌性蜘蛛愿意留存它们的精液）才会受到影响，目前尚没有定论—但是雌性蜘蛛吃掉她们的伴侣可以防止这些雄性蜘蛛将精液输送到她们的情敌手中。
　　Whatever the details, for male Leucauge argyra this behaviour gives a new meaning to the term "unsafe sex".
　　无论事情的来龙去脉如何，对于雄性长角银腹蛛而言，这种行为都给"危险性交"赋予了新的含义。