1·Long before Man lived on the Earth, there were fishes, reptiles, birds, insects, and some mammals.
在人类出现很早以前，地球上就出现了鱼类、爬虫类、鸟类和一些哺乳动物。
2·This division set the stage for allopatric speciation among populations of fishes and other marine species.
这种划分为鱼类和其他海洋物种的分区物种形成奠定了基础。
3·One potential problem is that opening the mouth to breathe detracts from the streamlining of these fishes and tends to slow them down.
一个潜在的问题是，张嘴呼吸会减损这些鱼类的流线型，可能使它们的速度减慢。
4·Scientists and engineers are beginning to study this ability of fishes in the hope of designing more efficient propulsion systems for ships.
科学家和工程师们开始研究鱼类的这种能力，希望能设计出更有效的船舶推进系统。
5·Second, it appears that closely related populations of fishes on both sides of the isthmus are starting to genetically diverge from each other.
其次，地峡两侧紧密相关的鱼类种群似乎开始在基因上彼此分化。