托福獨立口語話題及范文:物種演化出新特征

　　Animal

　　閱讀要點：

　　講座主題：Founder effect

　　內(nèi)容講解：少量物種從large population中脫離演化出獨特的特征

　　聽力要點：

　　教授例子：澳大利亞的小雛菊在大陸的種子很大，當(dāng)一小群漂洋過海到小島形成小群落后就演化成小種子的形態(tài)了。

　　托福綜合口語思路：

　　關(guān)于奠基者效應(yīng)，一族群的少數(shù)個體傳播到某地后，與原來的種族隔離,經(jīng)一段時間的繁衍之后，可能會生成新的物種。

　　托福綜合口語范文：

　　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.