The hunk and the show-off do not always get the girl

Sexual selection
雌雄淘汰（性选择）

The hunk and the show-off do not always get the girl
拥有健壮的体魄或是华丽的外表并不总能占有美眉

Males can take many routes to reproductive success
雄性能够通过多种渠道成功进行繁殖

Jun 3rd 2010 | From The Economist print edition




"BE FRUITFUL and multiply, and fill the Earth." Taken as an evolutionary imperative, that seems straightforward enough. But in reality, identifying the best way of doing it can be difficult, whether for individuals seeking romance, or scientists studying reproductive behaviour.

"要生养众多，遍满地面。（圣经创世纪中主的话）"用它来诠释进化法则，这看起来已足够直白。但是在现实世界中，无论是个体为了追寻浪漫爱情，还是科学家们为了研究生殖行为，找寻一种正确的方式来实践却都困难重重。

The scientists, at least, have made demonstrable progress. Two studies published this week―one by Jonathan Evans, of the University of Western Australia, the other by Tom Tregenza of the University of Exeter, in England―show that in fish and insects there is more than one path to mating success, and that the biggest, flashiest males do not always do better than their less assuming brethren.

科学家们最终还是做出了有理论支持的进展。这周有发表了两份研究报告，一份来自于西奥大学的乔纳森•埃文斯，另一份来自于英格兰埃克赛特大学的汤姆•特里金莎。研究报告表明，在鱼类和昆虫中成功交配的途径不止一条，并且体型最大、外表最光彩夺目的雄性并不总是优于那些看起来差些的同类。

In their quest for mates, some guppy males are show-offs. They conduct a decorous courtship in which they parade before their chosen belles. If a show-off's performance is sufficiently intense, his colour dramatic enough and his fins suitably ornamental, the female will welcome his advances―which explains the evolution of lavish tail fins and vivid, iridescent colouration. Other guppies, though, cannot be bothered with all this flummery. Instead, they go in for a copulatory ambush known as "sneaking".

一些雄性的孔雀鱼在追求伴侣时更注重外表。他们高雅地求爱，在中意的佳人面前游来游去。若这种炫耀的表演足够充满激情，雄鱼的颜色足够惹人注目，并且他的鱼鳍足够有吸引力，那么雌鱼便会欣然接受雄鱼接下来的行动。这些行为解释了为什么雄鱼会进化出过大的、有着鲜亮的彩虹般色彩的尾鳍。尽管如此，却有一些雄孔雀鱼懒得去做这种虚假的恭维，他们选择使用一种称作"偷袭"的伺机交配行为取而代之。

That is great for the sneak. Why, though, allow yourself to be ambushed if you are a female? Why mate with a second-class beau who cannot be bothered to bring you the fishy equivalent of roses and diamonds? The answer, as Dr Evans shows in the Proceedings of the Royal Society, is that sneaks are first-class in one particular department. Their sperm are much stronger swimmers than those of the show-offs. The energy that male fish expend on courtship comes at the expense of their semen.

这对偷袭者来说确实很棒。尽管如此，为何作为雌雄却认可自己被伺机交配呢？又为何要和那些懒得为你献上那些对鱼来说视作玫瑰与钻石的"爱情信物"的二等王子配对呢？埃文斯博士已在皇家学会学报中作出解释，原因在于从某种特殊的角度来看待的话偷袭者最为优秀。这些偷袭者的精子比那些花花公子们的游得更好。雄鱼花费在求爱行为上的能量来自于那些本来应该用于精液的部分。

For guppies, having vigorous sperm is valuable because females conduct multiple trysts. Sperm from several males must therefore compete to fertilise an egg. Dr Evans's research suggests that male guppies invest selectively in one of two different stages of the sexual competition. Some try to outcourt other males for access to females. Others try to outrace their rivals' sperm. The two strategies remain in equilibrium because, if one became rarer compared with the other, its practitioners would enjoy more individual success, passing their genes on preferentially and thus restoring the balance. Assuming, of course, that a preference for one strategy rather than another is inherited.

对于孔雀鱼来说，由于雌鱼会进行多次配对约会，来自不同雄鱼的精子在使卵子受精时必须要互相竞争，拥有充满活力的精子就显得很有价值。埃文斯博士的研究表明，雄性孔雀鱼有选择性地投入到两种不同的交配权争夺行为中的一种。一些尝试依靠求爱打败别的雄性来得到拥有雌鱼的机会。另一些则尝试依靠自己的精子比其他竞争对手的精子游得更快。这两种策略保持着相对平衡，原因如下，如果一种策略的使用相对少于另一种的话，那么对于使用这种策略的雄鱼个体就会享有更高的成功几率，进而优先地把自己的基因传递给下一代，从而使得两种策略间的平衡得以恢复。当然，前提是雄鱼对于繁殖策略的选择可以遗传。

So the last part of Dr Evans's study was to test whether the two strategies are, indeed, inherited. He found that they are. The sons of fertile, sneaky fathers do share these paternal traits, while sons of attractive fathers are equally appealing, but have similarly impoverished ejaculate.

这样，埃文斯博士的研究最后要做的，就是要验证这两种繁殖策略是否真的在实际上可以遗传。他发现结果是肯定的。具有突袭交配特性的雄鱼的雄性后代确实也具有这样的特性。而那些依靠具有吸引力的外表从而得到交配权的雄鱼的雄性后代也具有一样的吸引力以及和父代相似的退化了的射精能力。

The hunk and the troubadour
壮汉和游吟诗人

Dr Tregenza's study, published in Science, illuminates the similarly diverse mating strategies of crickets. Like guppies, male crickets compete for female favour―though by virtuoso chirping, rather than visual displays. But because previous systematic knowledge of cricket behaviour has come from studies done in the laboratory (studies, indeed, like Dr Evans's), some researchers have questioned whether this sort of behaviour actually contributes to reproductive success in the wild.

发表在《自然》杂志上的特里金莎博士的研究阐述说蟋蟀在繁殖中也会类似地采用不同的策略。像孔雀鱼一样，雄性蟋蟀也要争夺雌性的青睐，虽然他们使用的是音乐大师般地动听啁啾，而不是视觉盛宴。由于先前的对于蟋蟀的系统的认知来自于实验室内的研究（确实是和埃文斯博士类似的研究），一些研究者对于这类行为是否也同样在野生蟋蟀的成功繁殖中起到作用有着疑问。

To address that point, Dr Tregenza and his colleagues exposed a group of wild crickets to the Big Brother treatment. They trained video cameras on to 64 cricket burrows. They then captured, marked, released and tracked hundreds of crickets, and used the footage from the cameras to observe courtship, copulation, cohabitation and fights for dominance.

为澄清上述疑问，特里金莎博士和他的同事把一组野生蟋蟀用于"老大哥"试验（即一种时刻不干扰性监控）。为此，他们将摄像机对准64个蟋蟀洞穴。然后他们把捕来的上百的蟋蟀做上标记后，释放并追踪。研究小组用摄像机捕捉到的镜头来观察野生蟋蟀的求爱，交配，同居以及对于支配地位的争夺等行为。

In a heroic act of enlightened voyeurism, Dr Tregenza's colleague Rolando Rodríguez-Muñoz watched and analysed the resulting epic―all 250,000 hours of it. (He had the tapes on fast-forward and scanned 16 monitors at a time, looking for signs of movement that might indicate something interesting was going on.) By combining this video trove with data about each specimen's physical characteristics, genetics and offspring, the team then identified those traits that contribute to crickets' mating and reproductive success in the wild.

秉承一种英雄般的文明的性爱偷窥精神，特里金莎的同事，罗兰多•罗德里格斯•穆尼奥斯观察并分析了试验中得来的总共长达25万个小时的蟋蟀史诗。（他使用快进来观看录像带，并同时查看16个监视器的内容，来搜寻那些可能预示着蟋蟀正在进行研究小组感兴趣的活动的特征动作。）把这些录像中有价值的信息和那些来自于每一个试验样本的物理特征、基因以及后代的数据结合起来，研究小组得以识别出那些在野生蟋蟀的交配和成功繁殖后代中起到作用的特性。



Oh maiden fair, list to my lay
窈窕淑女，寤寐求之

Their results did indeed reinforce the established beauty standards for male crickets―"be large and be loud"―but with a twist. What they actually found was, "be large or be loud". Small males, in other words, could overcome the handicap of their stature and win mates through prodigious chirping. Larger males, by contrast, gained no additional mates through song. Like the guppies, then, different strokes were best for different folks. Moreover, being a dominant male brought no reproductive advantage. Subordinates sired the same number of offspring as dominants―a fact the researchers were able to confirm by genetic analysis.

试验结果彻彻底底地支持了已有的对于雄性蟋蟀的审美标准――"不但身材魁梧而且叫声响亮"――但是有细微差别。他们实际上发现的是，"要么身材魁梧，要么叫声响亮"。换句话说，体型瘦小的雄性可以依靠非凡响亮的鸣叫来弥补身材的不足之处，从而赢得伴侣。对比参照表明，身材魁梧的雄性并不会依靠鸣叫而获得额外的异性。这点和孔雀鱼相似，真是萝卜青菜，各有所爱。除此之外，成为具有统治地位的雄性在繁殖方面并没有优势。下等蟋蟀繁殖的后代并不比拥有统治地位的蟋蟀少――分析研究人员能够依靠基因分析来证实这一事实。

Once again, it looks as though two male strategies may be in equilibrium: the hunk and the troubadour, perhaps. What is clear from both studies, though, is that no matter how hard males compete, they will always be outwitted by the wiliest, most subversive competitors of all: females.

在这次试验中，不管是走壮汉路线还是走游吟诗人路线，两种雄性的求偶策略看上去也许再次处于相对平衡之中。尽管如此，两个试验皆清楚的表明了一个事实，那就是无论雄性竞争得如何激烈，他们最终都会被世上最狡猾的、最具有颠覆性的对手――雌性女王――以智取胜。