我們終于解開了為什么這只無聊的鳥有這么多五顏六色的小雞的奧秘

我們終于解開了為什么這只無聊的鳥有這么多五顏六色的小雞的奧秘

The American coot is a ubiquitous bird often seen waddling across the surfaces of North America's ponds and lakes. Their plumage is rather forgettable; a plain-black coloring that often blends with the murky waters where it swims.

美洲白骨頂是一種常見的鳥類，經(jīng)?？梢栽诒泵赖某靥梁秃幢砻婵吹剿鼡u擺的身影。它們的羽毛很容易被遺忘;一種純黑色，經(jīng)常與它游泳的渾濁的水混合在一起。

Why are coot chicks so much flashier than adults? (Photo: Casey Klebba/Wiki Commons [CC 4.0 License])

This unadorned look is all a ruse, however. Coots are hiding some rather mischievous behavior under that boring veneer, and while the adults can hide it well, it's written all over the feathers of their chicks, reports Phys.org.

然而，這種不加修飾的打扮完全是一種詭計。據(jù)Phys.org報道，白骨頂在無聊的外表下隱藏著一些相當(dāng)淘氣的行為，雖然成年白骨頂可以很好地隱藏這些行為，但這些行為卻寫在了雛鳥的羽毛上。

Scientists have long been befuddled by the discrepancy between the colors displayed by coot chicks and coot adults. Unlike their parents, chicks are born with fiery-orange feathers, beaks, and skin. Their flamboyancy seems to go against common evolutionary logic. Usually, colorful plumage in birds is utilized as a mating display; better-ornamented adults (most often males) are more likely to attract mates, and thus pass down their genes to the next generation.

科學(xué)家們一直對白骨頂雛鳥和成年白骨頂?shù)念伾町惛械嚼Щ?。與它們的父母不同，小雞出生時羽毛、喙和皮膚都是桔紅色的。他們的浮夸似乎違背了普遍的進化邏輯。通常，鳥類的彩色羽毛被用作求偶展示;裝飾得更好的成年人(通常是雄性)更有可能吸引配偶，從而將他們的基因傳給下一代。

But that can't be what's happening with coot chicks, because they lose their colors by the time they reach sexual maturity. Furthermore, chicks are typically more vulnerable to predators than adults are, so shouldn't that brilliant colorization make them even more susceptible to catching the eye of a hungry carnivore?

但那不可能是發(fā)生在白骨頂雛鳥身上的事，因為它們在性成熟時就會失去顏色。此外，雛鳥通常比成鳥更容易受到捕食者的攻擊，所以鮮艷的色彩難道不應(yīng)該使它們更容易被饑餓的食肉動物盯上嗎?

But now, scientists think they've solved the mystery, and the explanation hints at these birds' hidden wild side.

但是現(xiàn)在，科學(xué)家們認(rèn)為他們已經(jīng)解開了這個謎團，而且這個解釋暗示了這些鳥類隱藏的野性的一面。

In a new study published in Proceedings of the National Academy of Sciences, researchers explain how coot chick ornamentation was found to correlate with the order in which those chicks hatched. Coot hens lay about ten eggs, one per day, and the eggs usually hatch in the order in which they were laid. It turns out that the later a chick hatches, the more colorful it is.

在《美國國家科學(xué)院院刊》上發(fā)表的一項新研究中，研究人員解釋了如何發(fā)現(xiàn)白骨頂小雞的紋飾與這些小雞孵化的順序有關(guān)。白骨頂母雞每天產(chǎn)大約10個蛋，蛋通常是按它們產(chǎn)蛋的順序孵出來的。事實證明，小雞孵得越晚，顏色就越鮮艷。

Why should this weird correlation exist? The researchers realized it was a clue. For one, it indicates that it's not the chicks who are 'choosing' their colors, it must be their mothers.

為什么會存在這種奇怪的相關(guān)性?研究人員意識到這是一個線索。首先，這表明不是小雞“選擇”它們的顏色，而是它們的媽媽。

"That tells us the chicks can't be controlling their coloration, because they don't know where they are in the laying order. This is a maternal effect, presumably due to the mom putting more carotenoid pigments in the later eggs," explained Bruce Lyon, first author of the new study.

“這告訴我們，小雞不能控制它們的顏色，因為它們不知道它們在產(chǎn)卵順序中的位置。這項新研究的第一作者布魯斯·里昂解釋說:“這是一種母性效應(yīng)，可能是由于母親在后來的雞蛋中添加了更多的類胡蘿卜素。”

Further observation of coot nesting and laying behavior helps to reveal why it might be useful for coot mothers to color-code their chicks. Turns out, coots utilize a roguish parental tactic known as brood parasitism. They lay a number of eggs in the nests of other coots in an effort to fool them into raising their chicks for them. They typically do this with the first few eggs that they lay, reserving the later eggs for their own nests.

對白骨頂筑巢和產(chǎn)卵行為的進一步觀察有助于揭示為什么對白骨頂母親來說用顏色給雛鳥編碼是有用的。事實證明，白骨頂利用了一種被稱為幼體寄生的頑皮親代策略。它們會在其他白骨頂?shù)某怖锵潞芏嗟埃噲D愚弄它們，讓它們替自己喂養(yǎng)雛鳥。它們通常會在剛下蛋的時候這樣做，把后來的蛋留到自己的巢里。

So, the color coding can help them to identify which chicks are more likely to be their own, and not the orphans of some other sneaky coot. Researchers confirmed this strategy by noting how coot parents tend to pick favorites, making sure that the most colorful chicks are also the best fed.

因此，顏色編碼可以幫助它們識別哪些小雞更有可能是自己的，而不是其他一些狡猾的白骨頂?shù)墓聝?。研究人員通過觀察白骨頂父母傾向于挑選最喜歡的品種來證實這一策略，以確保色彩最鮮艷的雛鳥也能得到最好的喂養(yǎng)。

Coot breeding is a labyrinthine world, where these drab birds hide their true colors, secretly attempting to pull one over on each other.

白骨頂繁殖是一個迷宮般的世界，在那里這些單調(diào)的鳥隱藏他們的真實面目，秘密地試圖把對方拉過來。

"They're complicated birds. For over 20 years, we've been chipping away at understanding their reproductive behavior, and this is another interesting aspect of that," Lyon said.

“他們復(fù)雜的鳥類。20多年來，我們一直在研究它們的繁殖行為，這是其中另一個有趣的方面。”里昂說。

Further research into the genetics of this strategy should help to reveal the evolutionary logic behind it. How often are coots tricked into favoring chicks that aren't their own? The color-coding fail-safe must falter sometimes, otherwise it wouldn't make much sense for coots to go through with the whole bait-and-switch game to begin with.

對這種策略的遺傳學(xué)的進一步研究將有助于揭示其背后的進化邏輯。白骨頂有多少次被騙去喜歡不是自己的小雞?顏色編碼故障保險有時必須動搖，否則通過整個誘餌和開關(guān)游戲開始，它將沒有多大意義。

At the very least, the research shows that these birds have a lot more going on than their appearance might first suggest.

至少，研究表明，這些鳥比它們的外表看起來要復(fù)雜得多。