英语听力文摘 English Digest 393、单亲蜜蜂王国（在线收听）

How male honeybees can be without fathers? The reason lies in what’s called a haploidiploid system of sex determination. Approximately one-fifth of the animal kingdom, including ants and wasps, use this system. What it boils down to is that males are the result of unfertilized eggs whereas females are born from fertilized eggs.

But in bees there is an added complication since there is a gene that determines whether a bee will be male or female. It’s all in the numbers. Here’s how it works. 

A scientist isolated a gene called CSD, or Complimentary Sex Determiner. There are 19 different versions of this particular gene. It doesn’t matter which one of these 19 versions a male inherits from his mother; he’s going to be male because of the fact that he has only one of these CSD genes.

Accordingly, a female becomes a female because she has two CSD genes, except for one catch. And that catch is a bee in the bonnet of bee breeders.

Honeybee breeders often inbreed their bees in order to ensure desired traits. However, when bees are inbred it’s possible for fertilized eggs to end up with two copies of the same version of the CSD gene. The result is that the fertilized eggs would normally develop into workers or a new queen, develop into sterilized males.

Worker bees sense these sterile males when they’re still larvae, and they kill them. Before you know it, your honeybee colony has died out. The good news is that now that scientists understand more about how sex is determined among honeybees, they may discover solutions to this problem.

没有父亲的蜜蜂

雄蜂是如何在没有父亲的情况下生存的呢？其原因在于一种叫做haploidiploid的性别鉴定系统。包括蚂蚁王国及黄蜂帝国在内的约五分之一的动物王国都是采用这一性别鉴定系统。归根究底就是：雄性是由未受精卵繁育而来，而雌性则是由受精卵繁育而来的。

但是，这一系统在蜜蜂王国内使用会比较复杂。因为蜜蜂体内还有一个基因决定着蜜蜂的雌雄。这一切的关键在与数量。下面我们就来谈谈它是如何起作用的。

科学家们从蜜蜂体内分离出一种基因，叫做性别决定基因（简称CSD）。一般说来，这种基因在蜜蜂体内会有19个版本。哪一个性别决定基因是遗传自女蜂王的并无所谓。关键的是，如果说蜜蜂体内只有一个性别决定基因的话，毫无疑问，它必定是只雄蜂。

那么，有两个性别决定基因的就是雌性蜜蜂，但有一种蜜蜂是例外。那就是担任着繁殖下一代重任的女蜂王了。

蜜蜂一般都是近亲繁殖，以此确保下一代能具有一定的特性。然而，在进行近亲繁殖时，受精卵可能会拥有两个相同的性别决定基因的版本。自然而然的，这些受精卵会发育成为工蜂或是新一代的女蜂王，或是不育的雄蜂。

当这些不育的雄蜂还处在幼虫期时，若是被工蜂所发现，那小命也就没了。在人们知道之前，这一蜂群已然消亡。在这里，科学家们还是带来了一个好消息：科学家们对蜜蜂的性别决定机制已有了一定的了解，他们很快就会找出解决这个问题的方法。期待ing……

Note:   a bee in the bonnet  of    对……有独特的见解/想法…