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Science:鼠兔可能面临新的气候挑战:低氧

摘要 : 谈到在寒冷的天气里保暖这件事,鼠兔是冠军。但这种适应能力是有代价的,它可能让这些小小的山中居民难以应对气候变化。

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谈到在寒冷的天气里保暖这件事,鼠兔是冠军。但这种适应能力是有代价的,它可能让这些小小的山中居民难以应对气候变化。由于栖息地变热,住在低海拔的鼠兔做了一个避免灭绝的重要尝试:迁移到山上气温较低、海拔较高的地段。生物学家在上周于此召开的美国博物学家协会会议上报告说,即使它们能够实现这个改变,低海拔鼠兔可能仍无法应付高海拔地区的低氧环境。鼠兔有大约30个种类,分布在不同的海拔高度,这个物种很可能已经进化出了适应其居住环境的特别能力。为了评估高、低及中海拔地区鼠兔之间的功能差异,研究人员比较了来自海平面至海拔5000米范围内的10种鼠兔。他们对细胞的能量来源——线粒体中的三个基因进行了研究。这些基因是那些帮助利用氧气为身体产生化学能量的蛋白质的遗传密码。高海拔鼠兔的蛋白质似乎在这种转换中表现出较高的效率,这有助于解释它们是如何在空气稀薄的高海拔地区繁衍的。低海拔鼠兔则有一个改良版本的蛋白质,似乎可以用更少的“燃料”为细胞产生大量的热量。这对保暖来说非常有用,但让生存变得更为困难,如果它们必须迁徙到更高的海拔的话,因为在那里有效地使用氧气变得至关重要。而且如果鼠兔失败了,对整个生态系统都可能是一个麻烦:在青藏高原,它们是最常见的、在整个冬天都保持活跃的小型哺乳动物,是雪豹、黄鼠狼,甚至熊仅有的食物之一。此外,每只鼠兔的地下洞穴有多达60个入口,它们把这片土地的数个部分变成了“海绵”,吸收进季风季的雨水,减缓径流,让河流得以保持全年不涸。

原文链接:

Some pikas may soon face a new climate challenge: low oxygen

原文摘要:

PACIFIC GROVE, CALIFORNIA—Pikas are champs when it comes to keeping warm in cold weather. But this adaptation comes at a cost, one that may make it impossible for these small mountain-dwellers to cope with climate change. As their habitats heat up, pikas living at low elevations have one major shot at avoiding extinction: migrating to cooler, higher parts of the mountain. But even if they can make the shift, low-altitude pikas might not be able to cope with the low oxygen of higher altitudes, biologists reported here last week at a meeting of the American Society of Naturalists. Pikas, which include about 30 species all living at different altitudes, have likely evolved special adaptations for living wher they do. To assess functional differences between high-, low-, and midaltitude dwellers, researchers compared 10 species from elevations ranging from sea level to 5000 meters. They looked at three genes in the cell’s powerhouses, the mitochondria. These genes code for proteins that help use oxygen to generate chemical energy for the body. The proteins from high-altitude pikas appear to be very efficient at this conversion, which helps explain how they thrive high up wher the air is thin. Low-altitude pikas have a modified version that seems to generate lots of heat but less fuel for the cell. That’s great for keeping toasty, but it could make survival that much harder if they have to move to higher altitudes, wher efficient oxygen use is critical. And if the pika falters, it could mean trouble for an entire ecosystem: On the Tibetan Plateau, they are the most common small mammal to stay active through winter, providing one of the few foods for snow leopards, weasels, even bears. Moreover, with up to 60 entrances to each one’s underground burrows, they turn parts of the landscape into a “sponge” that soaks up monsoon rains and slows runoff, helping to keep rivers full year-round.

来源: Science 浏览次数:1

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