n99
加入时间: 2004/02/16
文章: 214
经验值: 871
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作者：n99 在 驴鸣镇 发贴, 来自 http://www.hjclub.org
他后来又作了具体说明：
“比如 受精卵上控制雄性生育的一个基因从y 染色体 转到x 染色体，我们这里 命名为 x(+)Y(-)这个受精卵发育成为一个雄性个体和正常的x(-)x(-)雌性交配，产生的后代f1 雄性均为x(-)Y(-) ，雌性x(+)x(-)。f1雄性这里都不能生育，如果这群生物和其总体处于相对隔离状态 只有群体内部交配进行繁殖的话用不了几代，x染色体 都被洗成x(+)。”
但在我这外行看来，这虽然能导致x(+)的新基因出现，而且能防止子1代互相婚配，但它并不能淘汰子代中的x(-)，也不能禁止子1代与野生型动物交配，因此x(+)新基因的比例还是得受哈代-温伯格定律支配。除非再度引入种群迁移假设，但那必然又要采用“每出现一个新基因，携带者们就得高飞远走”的不可能前提。
First let's talk about 哈代-温伯格定律 . If this law works for a species, the species must meet some preconditions something like a quite large population size, random mating and lack of any selections you mentioned. It is these requirements that at least 哈代-温伯格定律 is not true of some species.
For example, Neanderthal, a population ever lived in a very extended rang from Europe to Asia for 300 thousand years. Genetic evidence shows homo sapien and Neanderthal split up about 500 thousand years ago. But research proves their population size was never ever more than 10 thousand people during this long period of time. Another example is about chimpanzee. We all know human can infect with HIV and develop into AIDS. Like human, chimps are also susceptible to HIV infection but never develop into AIDS. Chimp and human share 96% same genetic make-up. Why chimps develop a different response to HIV? Genetic evidence shows a strong selection ,closely related to HIV infection was happening within chimp population.
Let’s go back to the case I mentioned.
但在我这外行看来，这虽然能导致x(+)的新基因出现，而且能防止子1代互相婚配，但它并不能淘汰子代中的x(-)，
Yes, it can. I explained it already yesterday. The answer is selection.
也不能禁止子1代与野生型动物交配，因此x(+)新基因的比例还是得受哈代-温伯格定律支配。
You are correct. It was my fault. I didn’t explained it clearly. I am still emphasizing an isolated population. It means after a couple of generations, this group ‘s genotypes are males x(+)Y(-) and females X(+) X(+) . If they backcross with wildtype, the males’ future male generations will be infertile. We can say this kind of “ reduction of gene flow”. Of course , the extreme case of reduction of gene flow is human’s 46 to 48 chromosomes change.
除非再度引入种群迁移假设，但那必然又要采用“每出现一个新基因，携带者们就得高飞远走”的不可能前提。
Migration doesn’t necessarily mean long distance travel. It means isolation ,sometime partly.
作者：n99 在 驴鸣镇 发贴, 来自 http://www.hjclub.org |
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有性繁殖给进化论带来的问题（修改稿）
