托福独立口语话题及范文:物种演化出新特征

　　Animal

　　阅读要点：

　　讲座主题：Founder effect

　　内容讲解：少量物种从large population中脱离演化出独特的特征

　　听力要点：

　　教授例子：澳大利亚的小雏菊在大陆的种子很大，当一小群漂洋过海到小岛形成小群落后就演化成小种子的形态了。

　　托福综合口语思路：

　　关于奠基者效应，一族群的少数个体传播到某地后，与原来的种族隔离,经一段时间的繁衍之后，可能会生成新的物种。

　　托福综合口语范文：

　　The lecture talks about founder effect, which refers to one way that nature can randomly create new species from existing populations. The professor explains further that when small populations of a species move to an area that is sufficiently distant or physically isolated from the original population, genes of the new population may be changed, and this new population will finally evolve into a new species. For example, a kind of daisy in Australia have big seeds, but some of the seeds are washed up on a small island which is isolated from the main land. Finally, this small populations evolve into a new species with small seeds.