时差N小时 计划生育 蚜虫的风格（在线收听）

If you keep a garden and have never been bothered by aphids, you are lucky. But one day you may find your rose bushes or bean plants covered--almost overnight--with these green, greedy sap-suckers. What allows aphids--and thousands of other species--to appear so fast is a trick these insects have developed for circumventing the old rule about the birds and the bees.

如果你有个花园，却从来没被蚜虫侵扰过，那你就很幸运了。但是你有可能发现园子里的玫瑰丛和豌豆叶上，几乎一夜之间爬满了绿幽幽，贪婪狂吃的蚜虫。是什么让这些蚜虫以及其它成千上万种虫子如此迅速地出现，这是虫子为规避鸟类和蜜蜂旧的食物链规则发展而来的诀窍。

During the summer months when aphid-food is plentiful, aphids reproduce through a process called "parthenogenesis," from the Latin words "virgin birth." What that means is that female aphids give birth to more female aphids without ever seeing a male. As soon as those daughters mature, they produce their own offspring, and so on.

在夏季的几个月期间，蚜虫的食物充足，它们会通过单性生殖方式繁殖后代，"parthenogenesis"这一词来源于拉丁语“virgin birth（圣灵感孕）”，意思就是雌性蚜虫不与雄性交配而生出许多雌性蚜虫。雌性蚜虫的女儿们一成熟，就立即繁衍自己的后代，如此以往。

Without the search for mates or the ensuing courtship rituals, parthenogenesis means big savings in time and energy: in just one season, a single aphid can give rise to billions of descendants.

单性生殖不需要蚜虫去寻找雄性配偶，更省略了随之而来的求爱仪式，因此十分节省时间和精力：在一个季节里，一只蚜虫会繁衍出十多亿后代。

But in the fall, fresh food gets harder to find and there'd no longer be any reason for producing so many offspring. So now a generation of aphids is born that includes males as well as females. And what happens next between the males and females is just what you might expect.

但是到了秋天新鲜食物很难找，这时就没必要去生产那么多子孙了。在新生一代蚜虫里既有雌性也有雄性。你可能会想到在雌雄性蚜虫之间接下来会发生什么。

Why aphids would turn from parthenogenesis to something as messy and inefficient as sex is another story, but in short, sexual reproduction is nature's way of shuffling the genes to create variety. Each of the offspring inherits a random mix of the parents' genes. And variety is what enables species to adapt and evolve as the environment changes.

为什么蚜虫会从单性生殖转为即紊乱又效率低下的有性生殖，这又是另一个故事了。简而言之，有性生殖是自然的基因重组方式，以创造多样的个体。每一个后代都遗传了父母随机组合的基因。多样性则是为了物种进化以适应环境的变化。

But when summer returns and the living is easy, the aphids give up on variety and reproduce once again in the fastest way they know how.

但是在下一个夏季，生存又变得容易起来，蚜虫就会放弃多样性，以它们掌握的最快的方式重新生殖。