标题: 邱政政听力11——讨论“生物学” [打印本页] 作者: 小七七 时间: 2011-9-14 18:55 标题: 邱政政听力11——讨论“生物学” 11.理科类段子：讨论“生物学”
Today, we are going to continue our discussion on social insects, focusing on the Argentine ants, which as you might guess is a species of ants that are natives to Argentina. We'll consider what happened to this type of ants after some members of the species move to California from their original habitat. OK, well, in Argentina, these Argentine ants behave like most ant species around the world. They fight other ants of the same species if those ants are from some other nests. But the Argentine ants living in California behave differently. Ants from different nests form a single large colony. Within this colony, there is little aggression among ants from different nests. And when they fight with insects from outside their colony, the Argentine ants can quickly recruit a huge army from their network of nests. This of course gives them advantages over other ants' species. So then, why do Argentine ants behave differently in California than they do in Argentina? Well, using genetic testing, researches found that all the Argentine ants in California were very similar genetically. You see, when the first Argentine ants came to California, their population must have been very small and all the later generations of Argentine ants there must have descended from the same few ancestors. So they are all closely related. This discovery is important, because for most social insects, membership in a colony is based on how closely related they are genetically.