Evolution: Greater than the sum of its parts
进化：青出于蓝而胜于蓝
It is rare for a new animal species to emergein front ofscientists’ eyes. But this seems to be happening in eastern North America.
在科学家看来，目睹一个新物种的出现十分罕见。可它正在美国东北部发生。
LIKE some people who mightrathernot admit it, wolves faced with a scarcity of potential sexual partners] are notbeneathlowering their standards. It was desperation of this sort, biologists reckon, that led dwindling wolf populations [in southern Ontario] to begin, a century or two ago,breeding widely with dogs andcoyotes.The clearance of forests for farming,together withthe deliberatepersecutionwhich wolves often sufferat the hand ofman, had made life tough for the species.That same forest clearance, though,bothpermitted coyotesto spread fromtheirprairiehomeland into areashithertoexclusivelylupine, andbroughtthe dogs that accompanied the farmersinto the mix.
如同那些不愿承认的人一般，当面临潜在配偶稀缺状况时，狼群只能降低其择偶标准。生物学家称，在一两个世纪前，这种绝望处境使得位于安大略省南部、数量骤减的狼群开始大范围与狗和土狼杂交。因耕地而清理森林，以及人类对狼群的蓄意猎捕，使得狼群生活艰难。可是，同样的清林行动，一方面迫使土狼离开草原故土而融于迄今为止排外的狼群，另一方面使跟随着农民的狗融入其中。
Interbreedingbetween animal species usually leads to offspring lessvigorousthan either parent—if they survive at all. But the combination of wolf, coyote and dog DNA that resulted from thisreproductive necessitygenerated an exception. The consequence has been booming numbers of an extraordinarily fit new animal (see picture) spreading through the eastern part of North America.
通常，动物间的杂交行为使得其后代即使存活，也不具备繁衍能力。然而，通过必须繁衍过程而混合的狼、土狼以及狗的DNA却是特外。（这种杂交行为）使这种DNA极端匹配的新物种数量激增并遍布北美东部。
Some call this creature the eastern coyote. Others, though, havedubbedit the “coy wolf”. Whatever name it goes by, Roland Kays of North Carolina State University, in Raleigh, reckons it now numbers in the millions. The mixing of genes that has created the coywolf has been more rapid,pervasiveandtransformationalthan many once thought. Javier Monzón, who worked until recentlyat Stony Brook University in New York state (he is now at Pepperdine University, in California) studied the genetic make-up of 437 of the animals, in ten north-eastern states plus Ontario. Heworked outthat, though coyote DNA dominates, a tenth of the average coywolf’s genetic material is dog and a quarter is wolf. The DNA from both wolves and dogs (the latter mostly large breeds, like Doberman Pinschers and German Shepherds), brings big advantages, says Dr Kays. At 25kg or more, many coywolves have twice the heft of purebred coyotes. With larger jaws, more muscle and faster legs, individual coywolves can take down small deer.A pack ofthem can even kill amoose.
一些学者称之为东部土狼，而另一些学者将其命名为“coywolf”。无论其命名如何，来自南加州大学的Roland Kays认为其数量数以万计。基因的杂交使得Coywolf更为比人们想象中更为快速、可变和数量繁多。曾经在纽约石溪大学工作的Javier Monzon（现任职于加州佩珀代因大学）在11个东北部州以及加大略对437只此杂交物种进行研究。其研究显示，虽土狼DNA占据主导地位，大约1/10的基因源自于狗，1/4的基因源自于狼。Kays博士称来自狼和狗（主要集中于大型犬，如德国短毛猎犬和德国牧羊犬）的基因为新物种带来了巨大优势。重达25kg或更多，coywolves重于纯种土狼二倍多。拥有更大下颚、更多肌肉和更快肢干，个体coywolves能够战胜小鹿，一群则能够杀死糜。
Coyotes dislike hunting in forests. Wolves prefer it. Interbreeding has produced an animalskilled atcatching prey in both open terrain and densely wooded areas, says Dr Kays. And even their criesblendthose of their ancestors. The first part of ahowlresembles a wolf’s (with a deep pitch), but this thenturns intoa higher-pitched, coyote-likeyipping.
“土狼不喜丛林捕猎，而狼却喜欢。两者的杂交使得新物种善于在开放地带和密林中捕杀猎物”，Kays博士称，“甚至新物种的嚎叫也是二者的混合。新物种的第一声嘶吼更像狼（低沉），而随后转变为一种与土狼类似的高频段的犬吠。”
The animal’s range hasencompassedAmerica’s entire north-east, urban areas included, for at least a decade, and is continuing to expand in the south-east following coywolves’ arrival there half a century ago. This is astonishing. Purebred coyotes never managed to establish themselves east of the prairies. Wolves were killed off in eastern forests long ago. But by combining their DNA, the two have given rise to an animal thatis able tospread into a vast and otherwise uninhabitable territory. Indeed, coywolves are now living even in large cities, like Boston, Washington and New York. According to Chris Nagy of the Gotham Coyote Project, which studies them in New York, the Big Apple already has about 20, and numbers are rising.
这种动物的足迹已遍布整个包括城市区域的整个美洲东北部长达10年之久，并跟随土狼半个世纪以前的足迹持续拓展至东南区域。这现象是惊人的。纯种土狼从未成功踏足草原东部。很久之前，狼群在东部丛林中被猎杀。但是二者DNA的混合使得新物种能够传播至广阔但不适宜居住的领地。的确如此，coywoleves现在甚至居住于大城市，如波士顿、华盛顿和纽约。据来自在纽约研究土狼的 the Gotham Coyote Project的Chris Nagy称，纽约大约有20只coywoleves，并且数量在上升。
Somespeculatethat this adaptability to city life is because coywolves’ dog DNA has made them more tolerant of people and noise, perhapscounteracting the genetic material from wolves—an animal that dislikes humans. And interbreeding may have helped coywolvesurbanizein another way, too, bybroadening the animals’ diet. Havingversatiletastesis handy forcity living. Coywolves eat pumpkins, watermelons and other garden produce, as well asdiscardedfood. They also eatrodentsand other smallishmammals. Manylawnsand parks are kept clear of thick underbrush, so catchingsquirrelsand pets is easy. Cats are typically eaten skull and all, with clues left only in the droppings.
一些人推断认为，之所以适应城市生活，在于coywolves体内狗基因使得他们更能够容忍人类和噪音，并可能抵消了来自于狼的对人类不喜的基因。杂交同样以另一种方式帮助coywolves城市化——扩大饮食范围。多样化饮食能够使城市生活更简单。coywolves能够吃南瓜、西瓜和其他园林作物，以及丢弃食物。他们还吃锯齿动物和其他小型哺乳动物。许多花园和草地保有浓密的下层树丛，因此，捕捉松鼠和宠物是简单的。猫被整体吞食，只留下一些血迹。
Thanks to thisbounty, an urban coywolf need occupy only half the territory it would require in the countryside. And getting into town is easy. Railways providecorridorsthat make the trip simple for animals as well as people.
一只城市coywolf仅占用一半于他们在城郊占用领土的一半，感谢这种慷慨。并且，进入城市是容易的。铁路所提供的通道，为人，也为动物，便利了路途。
Surviving once there, though, requires a low profile. As well as having small territories, coywolves have adjusted to city life by becomingnocturnal. They have also learned the Highway Code, looking both ways before they cross a road. Dr Kaysmarvels atthis “amazingcontemporaryevolution story that’s happening rightunderneath our nose”.
虽然生存下来，但其需要保持低调。如同占用较少领地，coywolves同样通过夜间活动而适应城市生活。它们也学会了高速公路规则，过马路前先看俩边。Kays博士惊叹于发生在我们注视下的当代进化故事。
Whether the coywolf actually has evolved into a distinct species is debated. Jonathan Way, who works in Massachusetts for the National Park Service, claims in a forthcoming paper that it has. He thinks itsmorphologicaland geneticdivergencefrom its ancestors is sufficient to qualify. But many disagree. One common definition of a species is a population that will not interbreed with outsiders. Since coywolves continue to mate with dogs and wolves, the argument goes, they are therefore not a species. But, given the way coywolves came into existence, that definition would mean wolves and coyotes should not be considered different species either—and that does not even begin to address whether domestic dogs are a species, or just anaberrantform of wolf.
是否Coywolf进化为一种新的物种还有待谈论。在Massachusetts的国家公园工作的Jonathan Way在一篇即将出版的论文中称coywolf已成为一种新物种。他认为与其祖先在形态学和基因上的分化使得他们足以成为新的物种。然而，许多人并不同意。有关物种的一个普遍接受的观点认为物种不能够与其他物种交配并产生后代。因为coywolves能够与狗和狼交配，因此他们不能够成为物种。然而，既然coywolves已诞生，根据这个定义意味着狼和土狼也不该被认为是不同物种，甚至不能够将家狗当作新物种，而是狼的一种变体形态。
In reality, “species” is a concept invented by human beings. And, as this argument shows, that concept is notclear-cut. What the example of the coywolf does demonstrate, though, is that evolution is not the simple process of one speciesbranching intomany that the textbooks might have you believe. Indeed, recent genetic research has discovered that evenHomo sapiensis partly a product ofhybridisation. Modern Europeans carry Neanderthal genes, and modern East Asians the genes of a newly recognised type of early man called the Denisovans. Exactly how this happened is unclear. But maybe, as with the wolves of southern Ontario, it was the only way that some of the early settlers of those areas could get a date.
实际上，物种仅仅是人类发明的一个概念。并且，如同争论显示，这个概念界定并不清晰。然而，coywolf这个例子的确显示了进化并非如同教科书教授一般的一个物种分化为多个的简单过程。事实上，最近基因学研究显示甚至智人也是杂交的产物。现代欧洲人具有穴居人的基因，而现代东亚人拥有最近被认可的丹尼索瓦人的基因。如何发生并不清楚。但，可能，如同安大略南部的狼群一半，仅仅因为早期的居住者能够获得一个配偶。
