房子重要还是传宗接代重要

Hermit Crab Equipment

"So, I never really thought I'd study penis size, but I sort of stumbled on this topic." Mark Laidre, a biologist at Dartmouth College. Laidre travels to Costa Rica to study hermit crabs, a species called Coenobita compressus. These land crabs do some interior remodeling of their adopted shells: they extensively hollow them out, removing struts called spiral columella, to give themselves some extra elbow room. The renovation renders the shells more precious to their owners - and to other covetous crustaceans as well.

"These more valuable shells, though, are also more easily stolen, since without the spiral columella inside the shell to grip onto, individuals are pretty liable to have their property snatched from them. Particularly when they are engaged in other activities, like copulation, which requires coming partway out of the shell."

Despite his work in the field, it wasn't until Laidre was wandering through a museum that he noticed something about his favorite crabs. "The really striking thing was that Coenobita compressus, the one whose social behavior I'd been studying for so many years, had an unusually large penis. In fact, bigger than any of the other species." The observation gave him an idea, which he dubbed the "private parts for private property" hypothesis. "In essence, the hypothesis posits that enlarged private parts can be an adaptation, extending a male's sexual reach and thus enabling both him and his partner to remain safely tucked away inside their shells while they copulate, thereby protecting the private property of their shells from being stolen during sex."

Darwin proposed a similar idea to explain why barnacles, which are stuck in one place, are so amply endowed. To test his "private parts for private property" hypothesis, Laidre sized up more than 300 male museum specimens, including hermit crabs that live on land and at sea. And he found that crabs that carried custom coverings had the most impressive carnal equipment. At the same time, species that got their shells off-the-shelf had bigger gear than did crabs that walked around with no shell at all. His results are revealed in the Royal Society journal Open Science.

"It's intriguing to think that this hypothesis might have greater generality beyond hermit crabs." But like a hermit crab encountering a humdrum shell, Laidre says he's going to leave that one alone. "For me, I'm much more curious about how forms of animal architecture and remodeling in the environment impact social behavior."

参考译文

我从没想过自己会研究阴茎尺寸,也是误打误撞才研究这个课题。达特茅斯学院的生物学家马克赖德尔说。赖德尔前往哥斯达黎加研究白住房。白住房的学名叫寄居蟹。这些陆生蟹会将它们的二手房做一些内部装修,移除那些叫螺旋囊轴的支柱,将寄居壳完全掏空,让自己有更大的活动空间。经过一番装修改造之后,家对于业主来说就变得更加珍贵,也会引来甲壳纲动物垂涎的目光。

房子升值了,却也更容易被盗了。因为没有内部的螺旋囊轴作为抓手,业主就有更大财产被盗的风险,尤其是他们从事其它活动的时候,比如当寄居蟹交配的时候,就需要将部分身体探出寄居壳外。

尽管赖德尔很有实践经验,可直到有一天参观博物馆才发现,他最爱的寄生蟹有一大特点。我研究寄居蟹社会行为多年,却没发现它的阴茎这么大,大得离奇,比其他物种都要大。这一观察让他突发奇想,想出了一个私处护私宅假说。简单地说,私处大体现了生物的适应性,它会延长雄性的性能力,从而让他和性伴侣在交配的同时安全地缩在各自的寄居壳之内,从而保护自己的私宅在性生活过程中不被盗。

达尔文也曾提出过类似理论,解释为何从不挪窝儿的藤壶被赋予了如此大的能力。为了测试他的私处护私宅假说,赖德尔仔细对比了三百多种雄性寄居蟹博物馆标本,包括海参和陆生两种。他发现,那些外壳经过二次改造的,性器官最大,同时,那些长了壳的要比没长壳的性器官大。它的研究结果发表在皇家学会开放科学期刊上。

这项假说很可能不止适用于寄居蟹,可能对其它动物也通用,想想就觉得有趣。如果寄居蟹碰到不好看的外壳,又会怎样呢?赖德尔说,这种情况他暂不研究。我更感兴趣的是,动物建筑结构和对环境的改造如何影响它的社交行为。

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