英语听力文摘 大灭绝
Coextinction
绝种是指生物群体逐渐消失的过程。物种和较大族群常态性的灭绝，并由更进步的形式所取代，这是进化的正常过程。然而，从化石的记录来看，有时会出现整个科目的动物和植物都突然消失的情形，这种现象称之为大灭绝。
Y:Down,you konw how when we think about species going extinct, we think of them as functioning separately from other species.
D:Oh!So we think about saving the whales, but don’t really think about any other species with which endangered whales interact.
Y:Right.Well,A study published in Science suggests that extinction is actually a lot more complicated. The problem is that extinction of one species can cause the extinction of a bunch of others.
Scientists call this process coextinction. For example, take hummingbird flower mites. If hummingbirds went extinct, the mites would go extinct too because they would have no way of getting from flower to flower. The same goes if the flowers on which these mites depend for nectar and pollen go extinct.
In fact, according to this study, if you add up all the affiliate species that are expected to go extinct if the species on the endangered list goes extinct, you’re looking at an additional sixty- three-hundred endangered species.
And also important to know as we try to focus conservation efforts, especially since some species have more affiliate species thann others. The army ant(行军蚁), for example, is host to over one hundred affiliate organisms, ranging from beetles and mites to ant birds. These kinds of species are keystone species in an evolutionary sense, and so are extremely important from a conservationstandpoint.
Even if coextinction isn’t the main reason for species extinction, it certainly is an insidious process that we can’t (1)afford to ignore.
Notes:
(1)afford to(有条件)做;能承担;买得起某物;支付的起
One can afford to lose anything, but dignity.
可以承受失去任何东西，但有尊严。
