(請先參閱：http://pansci.tw/archives/19645)
The temperature of a nest can affect a hatchling lizard's size, speed, and sex. Now, the reptiles can add smarts to the list. Researchers have found that lizards incubated in warmer environments may learn faster than others. The results are preliminary, but they suggest that a hotter climate could give some lizards a cognitive edge, potentially helping them escape predators.
巢的溫度會影響孵化出的蜥蝪大小、成長速度及性別。目前，此些爬蟲類的上述一覽表能添加上機敏這一項。研究人員們業已發現，在較暖和環境中孵化的蜥蝪，可能比其他蜥蝪學習更快。這是初步研究結果，不過他們暗示，較熱的氣候可能賦予某些蜥蝪認知優勢，潛在上有助於牠們避開獵食者。
Among the species poised to sharpen up is the three-lined skink (Bassiana duperreyi), a small, bug-eating lizard native to southeast Australia. The female skinks lay clusters of eggs under sunny rocks and logs, and their nests are heating up. University of Sydney herpetologist Richard Shine and his colleagues found that between 1997 and 2006, the lizards' nest temperatures increased by about 1.5°C—despite females' tendency to dig deeper nests and lay eggs earlier in the spring.
該物種中，顯現出使得較敏銳的是三線石龍子(Bassiana duperreyi)，一種原產於澳洲東南部的小型、食蟲蜥蝪。該種雌性石龍子，在陽光普照的岩石及原木下，產下成簇的蛋。因此，牠們的巢處於增溫中。澳洲雪梨大學爬蟲類學家Richard Shine及其同僚們發現，儘管雌性石龍子傾向挖更深的巢，且更早於春天下蛋。不過於1997到2006年間，此些蜥蝪巢的溫度，增加達大約1.5℃。
圖1. three-lined skink (圖援用自：
http://www.dpiw.tas.gov.au/inter,nsf/WebPages/BHAN-55Z2TZ?open)
Lizard moms might do well to accept the climbing temperatures—at least for now. Nests at the hot end of normal are more likely to produce fast-running hatchlings with an even sex ratio. (Cooler nests have more males, which are hardier in the cold—but an equal ratio could lead to more baby lizards overall.) Joshua Amiel, a Ph.D. student in Shine's lab, wondered if the warmer embryos' brains might develop differently, too. He collected wild females and nestled their eggs in individual glass dishes of sand and vermiculite. Half went to a warm chamber with an average temperature of 22°C, the others to an incubator averaging 16°C, until they hatched.
至少就目前而言，蜥蝪媽媽相當能接受攀升的溫度。處於正常熱度極限的巢，較可能招致孵化出具有均勻性別比例、爬行快速的幼蜥蝪。(較冷的巢孵化出較多更耐寒的雄蜥蝪，不過整體上均等的比例，會導致更多的蜥蝪寶寶。)Shine實驗室的博士生Joshua Amiel疑惑，是否較溫熱下的胚胎大腦發育，也有差異。他收集了野生雌蜥蝪，並將牠們的蛋安置於，分別含有沙及蛭石(一種加熱後會顯著膨脹的含水層狀矽酸鹽礦物)的玻璃盤中。半數被送入平均溫度22℃的溫室中，其他被送入平均16℃的孵化器中，直到牠們孵化出。
When the skinks were a few weeks old and smaller than your pinkie finger, Amiel gave them a simple learning test. Each lizard was placed in a 24°C cage with two hiding places—overturned plastic flower-pot trays with entry holes cut in the sides. But one was a decoy, its opening blocked with Plexiglas. Clever lizards, after bumping the window a few times, should give up on the fake hiding place and go to only the good one, Amiel reasoned.
當此些石龍子幾星期大且比人的小手指小時，Amiel給予牠們一項簡單的學習測試。每隻蜥蝪被放在一個溫度24℃、具有兩個藏身處的籠子中，也就是於兩邊具有開口之翻轉過來的塑膠花盆托盤。不過，有個開口是引誘的地方，其被普列克斯玻璃(Plexiglas：一種用聚甲基丙烯酸甲酯製成的透明塑膠材料)所阻塞。Amiel推斷，在碰撞此阻隔物幾次後，機靈的蜥蝪會對此假的藏身處感到絕望，而僅跑向確實可出去的開口。
He tested each lizard 16 times over 4 days, touching its tail with a paintbrush to spook it into hiding. Amiel logged an "error" every time a lizard bumped its nose on the Plexiglas window and logged a successful "escape" if it found the real hiding place in 30 seconds.
使用畫筆碰觸蜥蝪的尾巴來使其驚嚇躲藏，Amiel於四天期間，測試每隻蜥蝪16次。他記錄了，每隻蜥蝪錯誤碰撞上阻塞Plexiglas的開口次數，及在30秒內發現真正可藏身處，而成功避開的次數。
Lizards from warm nests and cool nests started out making a "relatively equal" number of errors, Amiel says. But the warm-incubated lizards improved, making on average one or two more escapes during the second 2 days than they had during the first 2 days. Cool-incubated lizards showed no such gains, Amiel and Shine report online today in Biology Letters. If the same effect plays out in nature, hatchlings from warm nests may have a better chance of escaping predators, be they cats or kookaburras.
Amiel表示，來自暖巢及冷巢的蜥蝪開始做出相對等數的錯誤。不過，暖孵化出的蜥蝪改善了，牠們在後兩天期間，平均比前兩天多做出一次或兩次以上的避開行為。Amiel及Shine於2012年1月10日網路版《生物學記事》期刊中記述，冷孵化出的蜥蝪沒有顯現此類進展。倘若於自然界中，演出相同的效應，則從暖巢孵化出的蜥蝪可能具有更佳避開，貓或笑翠鳥等獵食者的機會。
Incubation temperature changes so much about a lizard's development that "it makes sense" for it to affect learning ability, too, says Barry Sinervo, a herpetologist at the University of California, Santa Cruz. But, he adds, each species probably has an optimum incubation temperature above which its brain power declines again—so any benefit that lizards get from climate change is likely to be temporary and patchy.
美國加州大學聖克魯斯分校的爬蟲類學家，Bary Sinervo表示，孵化溫度對於蜥蝪的發育變化這麼大，以至於也影響學習能力"是說得通的"。不過他附言，每一物種很可能皆有最適宜的孵化溫度，超出此溫度其腦力會再度下降。因此，蜥蝪從氣候變遷獲得的任何效益，可能是暫時且不完全的。
Gordon Burghardt, who studies reptile behavior at the University of Tennessee, Knoxville, agrees that the study is "important" for linking learning with climate. But he's cautious about the results, in part because the experiments weren't blinded: Amiel knew which lizards came from warm and cold nests, and he knew which hiding place was the good one. Without blinding, Burghardt says, unconscious biases or even inadvertent behavioral cues from the experimenter can be "really problematic."
美國田納西大學(位於田納西州諾克斯維爾市)研究爬蟲類行為的Gordon Burghardt認同，該項研究將學習與氣候聯繫在一起的重要性。不過，他對於此些研究結果是審慎的，部分是因為此些試驗並非盲目的：Amiel知曉哪些蜥蝪來自暖巢及冷巢，且知曉哪一個是正確藏身處。不過Burghardt表示，真正的問題是，會沒有盲目、潛意識的偏見，或甚至來自試驗者粗心大意的行為線索？
Amiel acknowledges that the study is preliminary, but he says he's eager to follow up with a new round of experiments and several cognitive tasks. "We've got a whole bunch of eggs that are just about to hatch now," Amiel says.
Amiel坦承，這是一項初步研究。不過他表示，渴望進一步進行新一輪的試驗及若干認知的研究工作。Amiel宣稱：「目前，他們已經取得一堆即將孵化的蜥蜴蛋。」
原文網址：https://www.sciencemag.org/news/2012/01/could-climate-change-alter-lizard-learning
翻譯：許東榮
離婚證人
留言列表
