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全球变暖致北美蝾螈体形变小

2014-03-27    来源:新华网    【      美国外教 在线口语培训

Salamanders in North America getting smaller due to global warming: study

Wild salamanders living in some of North America's best salamander habitat are getting smaller due to global warming, a U.S. study said Tuesday.

The study, published in the journal Global Change Biology, said the salamanders are forced to burn more energy as their surroundings get warmer and drier.

Scientists have predicted that some animals will get smaller in response to climate change, and this is strong confirmation of that prediction, the researchers said.

The study examined museum specimens caught in the Appalachian Mountains from 1957 to 2007 and wild salamanders found at the same sites in 2011 and 2012.

The salamanders studied from 1980 onward were, on average, eight percent smaller than their counterparts from earlier decades, the study said.

Overall, six salamander species got significantly smaller, while only one got slightly larger between 1957 and 2012, it said. On average, each generation was one percent smaller than its parents' generation.

The researchers also compared changes in body size to the animals' location and their sites' elevation, temperature and rainfall. They found the salamanders shrank the most at southerly sites, where temperatures rose and rainfall decreased over the 55- year study.

"This is one of the largest and fastest rates of change ever recorded in any animal," said Karen Lips, an associate professor of biology at the University of Maryland and the study's senior author.

"We don't know exactly how or why it's happening, but our data show it is clearly correlated with climate change," she said.

To find out how climate change affected the animals, the researchers used a computer program to create an artificial salamander, which allowed them to estimate a typical salamander's daily activity and the number of calories it burned.

The simulation showed the modern salamanders were just as active as their forbears had been. But to maintain that activity, they had to burn seven to eight percent more energy. That's because cold-blooded animals' metabolisms speed up as temperatures rise, they explained.

To get that extra energy, salamanders must make trade-offs, Lips said. They may spend more time foraging for food or resting in cool ponds, and less time hunting for mates. The smaller animals may have fewer young, and may be more easily picked off by predators.

"Right now we don't know what this means for the animals," Lips said. "If they can start breeding smaller, at a younger age, that might be the best way to adapt to this warmer, drier world. Or it may be tied in with the losses of some of these species."

The research team's next step will be to compare the salamander species that are getting smaller to the ones that are disappearing from parts of their range.

相关新闻:美国一项新研究发现,过去几十年中,北美一些地区的蝾螈体形变小,原因可能是它们为适应变热变干燥的栖息地,不得不消耗掉更多的能量。科学家说,这是第一次有研究证实全球变暖会影响动物的体形。

美国马里兰大学研究人员25日在《全球变化生物学》上报告说,他们研究了1957年至2007年之间在北美阿巴拉契亚山脉捕捉制成的蝾螈标本,以及2011年和2012年在相同地点发现的野生蝾螈。结果发现,1980年以后的蝾螈的体形要比几十年前的蝾螈平均小8%。

进一步研究发现,1957年至2012年间,阿巴拉契亚山脉只有一种蝾螈的体形稍稍变大,却有6种蝾螈的体形“显著变小”,平均每一代比上一代体形小1%。

研究人员还分析了蝾螈身体变化与海拔、温度和降水之间的联系。结果发现,在温度升高但降水减少最明显的阿巴拉契亚山脉南部低海拔地区,蝾螈体形缩小最为明显。

研究负责人、马里兰大学副教授卡伦·利普斯说:“我们的数据表明,这与气候变化明显相关。”

研究人员开发了一个电脑程序,模拟蝾螈的日常活动与能量消耗。结果发现,现代蝾螈的日常活动与其祖先相同,但随着气温升高,作为冷血动物,蝾螈要保持同样的活动程度,身体代谢必须加快,导致能量消耗增加。 (新华网)



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