【英语时差8,16】M&M巧克力豆与遗传漂变(上)(在线收听

 We’ve discussed before how endangered species are at risk from the increased likelihood of inbreeding, which leads to unhealthy offspring. But there’s another danger to letting the numbers of animals in a given species become too low. It’s called genetic drift. Genetic drift is the term biologists use to describe the gradual loss of certain genes from a species–genes that may have been very important for that species’ survival. How Can Animals Lose Genes? It’s kind of like reaching into a bag of M&Ms. If you take out a hundred M&Ms you are sure to get all the colors at least once. If you only take out ten, you may well miss a color. And if by chance you haven’t missed a color, try it again. Very soon you will come up with, say, no reds.

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