[全文听写]：本文 三处 破折号。今天的速度不快，但是音效还挺频繁的，注意连接。
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Cope's
University of Missouri
Carl Gerhardt
Mitch Tucker
the Proceedings of the Royal Society B-Biological Sciences
The eastern grey tree frog looks exactly like the closely related Cope's grey tree frog. The big difference between the two species is beneath the surface — the eastern has twice the number of chromosomes as does the Cope's. Having more sets of chromosomes makes the cells of the eastern frog larger than the cells found in the Cope's. And those bigger cells makes the eastern's song just a little deeper. Now University of Missouri researcher Carl Gerhardt and his student Mitch Tucker have determined that the slight difference in the calls — here's the eastern again and here's the Cope's — is how the females know which species' males to buddy up with: the ones with the same chromosome number that they have. The work is in the Proceedings of the Royal Society B-Biological Sciences. Speciation is often caused by a geographic barrier that keeps populations from mating. But the tree frog situation may be a rare case in which chromosome duplication, and its subsequent effects, presented a reproductive barrier. As in humans, it comes down to whether he calls.
两种亲缘相关的蛙类差异在其染色体数目，鸣叫声低沉的那种有助于雌性寻找配偶。 东方灰色树蛙外表上看起来和它的近亲Cope灰色树蛙很像。而它们两个种类之间的最大差异并没有在外表上显示出来---东方灰色树蛙的染色体数目比Cope的多一倍。由于染色体数目较多，东方树蛙的细胞个头比Cope大一些，并且这些大个的细胞使得东方树蛙的叫声更低沉一些。 密苏里州大学的Carl Gerhardt和他的学生 Mitch Tucker 已经发现二者遗传差异的表型反映在叫声上有点儿不同-----这个是东方树蛙再叫一下，而这个是Cope树蛙的叫声---正是如此，雌蛙才能区别这两种雄性个体从而进行正确交配：有同样数目染色体的两性物种正确识别彼此。这项工作成果已经发表在《皇家科学杂志B的生物科学》杂志上。 一般是由于地域屏障阻止种群间的交配，从而形成物种差异。但是树蛙的这个情况比较特殊，由于染色体数目复制翻倍并由此产生生殖屏障最终形成了两种不同的树蛙。如果这种染色体加倍的情况发生在人类身上，那么产生的个体是否会叫可就说不准了…… —Steve Mirsky ————————by hyjtb