科学家用基因解释了为何大小熊猫都以竹子为食
Chinese researchers said Monday they have uncovered the genetic basis of why giant pandas and red pandas have evolved independently to have shared features such as a bamboo-based diet and false thumb.
日前，来自中国的研究人员表示，他们已经发现了大熊猫和小熊猫的遗传基础，可以解释为什么这两种动物独立进化，但是却又具备喜食竹子和伪拇指等共同特点。Despite being classified as carnivores, both giant pandas and red pandas, which separately evolved from meat-eating ancestors and diverged from each other more than 40 million years ago, subsist almost entirely on bamboo -- a phenomenon termed convergent evolution, where similar traits arise in two unrelated or distantly related species.
大熊猫和小熊猫都是分别从食肉祖先进化而来，并且已经分开超过4000万年。尽管这两种动物都被归类为食肉动物，但是它们却几乎完全依赖竹子生存--这种现象被称为趋同进化，相似的性状会在出现在两个无关、或者关系较远的物种身上。Additionally, both species possess a false thumb, which enables the animals to adroitly grasp bamboo.
此外，这两个物种都具有伪拇指，这可以使它们熟练地抓住竹子。
To uncover the genetic basis of such convergence, Fuwen Wei and colleagues from the Institute of Zoology, part of the Chinese Academy of Sciences, sequenced the genome of a wild male red panda and compared it with the reassembled genome of the giant panda.
为揭开这种趋同现象的遗传基础，魏辅文和他中国科学院动物研究所的同事们对野生雄性小熊猫的基因组进行了测序，并与大熊猫重新排列过后的基因组进行对比。Their findings were published in the recent issue of U.S. journal Proceedings of the National Academy of Sciences.
他们的发现被刊载在美国杂志《美国国家科学院学报》最新一期上。The results confirmed that giant pandas belong to the family Ursidae together with polar bears, whereas red pandas belong to the superfamily Musteloidea together with ferrets and that the two species separated 47.5 million years ago, slightly earlier than previous molecular-based estimate of 43 million years ago.
结果证实，大熊猫和北极熊一样属于熊科，而小熊猫则和雪貂一样属于鼬科大家族，这两个物种在大约4750万年前分离，略早于先前根据分子估计的4300万年。Genome analysis revealed signs of adaptive convergence in 70 genes, including two genes, known as DYNC2H1 and PCNT, that are involved in false thumb development.
基因组分析显示70个适应性趋同的基因，包括两个调控熊猫伪拇指发育的重要基因DYNC2H1和PCNT。Giant and red panda genomes also share 10 pseudogenes, or "false" genes, which look like real genes but have no apparent function.
大熊猫和小熊猫的基因组里还共有10个假基因，这些基因看起来跟真的一样，但是却没有明显的功能。
