Evolution: Greater than the sum of its parts
進(jìn)化：青出于藍(lán)而勝于藍(lán)
It is rare for a new animal species to emergein front ofscientists’ eyes. But this seems to be happening in eastern North America.
在科學(xué)家看來(lái)，目睹一個(gè)新物種的出現(xiàn)十分罕見(jiàn)诲侮。可它正在美國(guó)東北部發(fā)生隆夯。
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.
如同那些不愿承認(rèn)的人一般，當(dāng)面臨潛在配偶稀缺狀況時(shí)吆视，狼群只能降低其擇偶標(biāo)準(zhǔn)错览。生物學(xué)家稱，在一兩個(gè)世紀(jì)前澳盐，這種絕望處境使得位于安大略省南部、數(shù)量驟減的狼群開(kāi)始大范圍與狗和土狼雜交令宿。因耕地而清理森林叼耙，以及人類對(duì)狼群的蓄意獵捕，使得狼群生活艱難粒没∩竿瘢可是，同樣的清林行動(dòng)癞松，一方面迫使土狼離開(kāi)草原故土而融于迄今為止排外的狼群爽撒，另一方面使跟隨著農(nóng)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.
通常响蓉，動(dòng)物間的雜交行為使得其后代即使存活硕勿，也不具備繁衍能力。然而枫甲，通過(guò)必須繁衍過(guò)程而混合的狼源武、土狼以及狗的DNA卻是特外。（這種雜交行為）使這種DNA極端匹配的新物種數(shù)量激增并遍布北美東部言秸。
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.
一些學(xué)者稱之為東部土狼软能，而另一些學(xué)者將其命名為“coywolf”迎捺。無(wú)論其命名如何举畸，來(lái)自南加州大學(xué)的Roland Kays認(rèn)為其數(shù)量數(shù)以萬(wàn)計(jì)〉手Γ基因的雜交使得Coywolf更為比人們想象中更為快速抄沮、可變和數(shù)量繁多。曾經(jīng)在紐約石溪大學(xué)工作的Javier Monzon（現(xiàn)任職于加州佩珀代因大學(xué)）在11個(gè)東北部州以及加大略對(duì)437只此雜交物種進(jìn)行研究岖瑰。其研究顯示叛买，雖土狼DNA占據(jù)主導(dǎo)地位，大約1/10的基因源自于狗蹋订，1/4的基因源自于狼率挣。Kays博士稱來(lái)自狼和狗（主要集中于大型犬，如德國(guó)短毛獵犬和德國(guó)牧羊犬）的基因?yàn)樾挛锓N帶來(lái)了巨大優(yōu)勢(shì)露戒。重達(dá)25kg或更多椒功，coywolves重于純種土狼二倍多捶箱。擁有更大下顎、更多肌肉和更快肢干动漾，個(gè)體coywolves能夠戰(zhàn)勝小鹿丁屎，一群則能夠殺死糜。
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.
“土狼不喜叢林捕獵旱眯，而狼卻喜歡晨川。兩者的雜交使得新物種善于在開(kāi)放地帶和密林中捕殺獵物”，Kays博士稱删豺，“甚至新物種的嚎叫也是二者的混合共虑。新物種的第一聲嘶吼更像狼（低沉），而隨后轉(zhuǎn)變?yōu)橐环N與土狼類似的高頻段的犬吠吼鳞】囱粒”
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.
這種動(dòng)物的足跡已遍布整個(gè)包括城市區(qū)域的整個(gè)美洲東北部長(zhǎng)達(dá)10年之久，并跟隨土狼半個(gè)世紀(jì)以前的足跡持續(xù)拓展至東南區(qū)域赔桌。這現(xiàn)象是驚人的供炎。純種土狼從未成功踏足草原東部。很久之前疾党，狼群在東部叢林中被獵殺音诫。但是二者DNA的混合使得新物種能夠傳播至廣闊但不適宜居住的領(lǐng)地。的確如此雪位，coywoleves現(xiàn)在甚至居住于大城市竭钝，如波士頓、華盛頓和紐約雹洗。據(jù)來(lái)自在紐約研究土狼的 the Gotham Coyote Project的Chris Nagy稱香罐，紐約大約有20只coywoleves，并且數(shù)量在上升时肿。
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.
一些人推斷認(rèn)為庇茫，之所以適應(yīng)城市生活，在于coywolves體內(nèi)狗基因使得他們更能夠容忍人類和噪音螃成，并可能抵消了來(lái)自于狼的對(duì)人類不喜的基因旦签。雜交同樣以另一種方式幫助coywolves城市化——擴(kuò)大飲食范圍。多樣化飲食能夠使城市生活更簡(jiǎn)單寸宏。coywolves能夠吃南瓜宁炫、西瓜和其他園林作物，以及丟棄食物氮凝。他們還吃鋸齒動(dòng)物和其他小型哺乳動(dòng)物羔巢。許多花園和草地保有濃密的下層樹(shù)叢，因此，捕捉松鼠和寵物是簡(jiǎn)單的竿秆。貓被整體吞食炭臭，只留下一些血跡。
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僅占用一半于他們?cè)诔墙颊加妙I(lǐng)土的一半袍辞，感謝這種慷慨鞋仍。并且，進(jìn)入城市是容易的搅吁。鐵路所提供的通道威创，為人，也為動(dòng)物谎懦，便利了路途肚豺。
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”.
雖然生存下來(lái)，但其需要保持低調(diào)界拦。如同占用較少領(lǐng)地吸申，coywolves同樣通過(guò)夜間活動(dòng)而適應(yīng)城市生活。它們也學(xué)會(huì)了高速公路規(guī)則享甸，過(guò)馬路前先看倆邊截碴。Kays博士驚嘆于發(fā)生在我們注視下的當(dāng)代進(jìn)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進(jìn)化為一種新的物種還有待談?wù)擈韧Ｔ贛assachusetts的國(guó)家公園工作的Jonathan Way在一篇即將出版的論文中稱coywolf已成為一種新物種日丹。他認(rèn)為與其祖先在形態(tài)學(xué)和基因上的分化使得他們足以成為新的物種。然而蚯嫌，許多人并不同意哲虾。有關(guān)物種的一個(gè)普遍接受的觀點(diǎn)認(rèn)為物種不能夠與其他物種交配并產(chǎn)生后代。因?yàn)閏oywolves能夠與狗和狼交配择示，因此他們不能夠成為物種束凑。然而，既然coywolves已誕生栅盲，根據(jù)這個(gè)定義意味著狼和土狼也不該被認(rèn)為是不同物種汪诉，甚至不能夠?qū)⒓夜樊?dāng)作新物種，而是狼的一種變體形態(tài)剪菱。
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.
實(shí)際上摩瞎，物種僅僅是人類發(fā)明的一個(gè)概念拴签。并且孝常，如同爭(zhēng)論顯示，這個(gè)概念界定并不清晰蚓哩。然而构灸，coywolf這個(gè)例子的確顯示了進(jìn)化并非如同教科書教授一般的一個(gè)物種分化為多個(gè)的簡(jiǎn)單過(guò)程。事實(shí)上岸梨，最近基因?qū)W研究顯示甚至智人也是雜交的產(chǎn)物∠舶洌現(xiàn)代歐洲人具有穴居人的基因稠氮，而現(xiàn)代東亞人擁有最近被認(rèn)可的丹尼索瓦人的基因。如何發(fā)生并不清楚半开。但隔披，可能，如同安大略南部的狼群一半寂拆，僅僅因?yàn)樵缙诘木幼≌吣軌颢@得一個(gè)配偶奢米。
