Hardy-Weinberg Equilibrium · 哈迪-温伯格平衡
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| Hardy-Weinberg equilibrium/ˈhɑːdi ˈwaɪnbɜːɡ ˌiːkwɪˈlɪbrɪəm/ | 哈迪-温伯格平衡 | hā dí - wēn bó gé píng héng |
What if nothing is changing?
- Evolution is a change in allele frequency — but what if the frequencies hold still?
- Imagine a population where no allele gets more or less common.
- Such a population is not evolving.
- This imaginary steady state is called Hardy-Weinberg equilibrium.
如果什么都没在变呢?
- 进化是等位基因频率的改变——但如果频率静止不动呢?
- 想象一个没有任何等位基因变得更常见或更少见的种群。
- 这样一个种群不进化。
- 这个假想的稳定状态叫做哈迪-温伯格平衡。
A non-evolving baseline
- Hardy-Weinberg equilibrium 哈迪-温伯格平衡 describes a population whose allele frequencies stay constant.
- It is a theoretical baseline — a picture of no evolution.
- We compare real populations against it.
- If reality does not match, something is causing evolution.
一个不进化的基线
- 哈迪-温伯格平衡(Hardy-Weinberg equilibrium)描述一个等位基因频率保持不变的种群。
- 它是一个理论的基线——一幅没有进化的图景。
- 我们把真实的种群与它比较。
- 如果现实不符,就有什么东西在引起进化。
A population in Hardy-Weinberg equilibrium is one that is… · 一个处于哈迪-温伯格平衡的种群是一个……的种群。
In Hardy-Weinberg equilibrium, allele frequencies do not change — the population is not · 不 evolving. · 在哈迪-温伯格平衡中,等位基因频率不改变——种群不进化。
The equation
- For two alleles, let $p$ be one allele's frequency and $q$ the other's, with $p + q = 1$.
- The genotype frequencies follow $p^2 + 2pq + q^2 = 1$.
- Here $p^2$ is homozygous dominant, $q^2$ homozygous recessive, and $2pq$ heterozygous.
- From an observed $q^2$ you can find $q$, then $p$, then every genotype frequency.
方程
- 对两个等位基因,设 $p$ 是一个等位基因的频率、$q$ 是另一个的,且 $p + q = 1$。
- 基因型频率遵循 $p^2 + 2pq + q^2 = 1$。
- 这里 $p^2$ 是纯合显性,$q^2$ 是纯合隐性,$2pq$ 是杂合。
- 从观察到的 $q^2$ 你能求出 $q$,再求 $p$,然后每个基因型的频率。
Conditions for no evolution · 不进化的条件
Step through the conditions a population must meet to stay in Hardy-Weinberg equilibrium - break any one and it evolves. · 一步步走过一个种群保持哈迪-温伯格平衡必须满足的条件——打破任何一个,它就进化。
The Hardy-Weinberg equation is $p^2 + 2pq + q^2 = 1$. What does $q^2$ represent? · 哈迪-温伯格方程是 $p^2 + 2pq + q^2 = 1$。$q^2$ 代表什么?
$q^2$ is the frequency of the homozygous recessive genotype (aa); $p^2$ is homozygous dominant, $2pq$ heterozygous. · $q^2$ 是纯合隐性基因型(aa)的频率;$p^2$ 是纯合显性,$2pq$ 是杂合。
If $q^2 = 0.09$, what is the recessive allele frequency $q$? · 如果 $q^2 = 0.09$,隐性等位基因频率 $q$ 是多少?
$q = \sqrt{0.09} = 0.3$. Then $p = 1 - q = 0.7$. · $q = \sqrt{0.09} = 0.3$。然后 $p = 1 - q = 0.7$。
The five conditions
- Equilibrium holds only if no evolutionary force is acting.
- That means: no natural selection, no migration, and no new mutations.
- It also needs random mating and a very large population.
- Break any one of these, and the frequencies shift — the population evolves.
五个条件
- 只有在没有进化力量起作用时,平衡才成立。
- 那意味着:没有自然选择、没有迁移、没有新突变。
- 它还需要随机交配和一个非常大的种群。
- 打破这些中的任何一个,频率就移动——种群进化。
If natural selection acts on a population, it is no longer in Hardy-Weinberg equilibrium. · 如果自然选择作用于一个种群,它就不再处于哈迪-温伯格平衡。
Selection breaks a required condition, so the frequencies change and the population evolves. · 选择打破了一个必需的条件,所以频率改变,种群进化。
Select all · 所有 conditions required for Hardy-Weinberg equilibrium. · 选出哈迪-温伯格平衡所需的所有条件。
Equilibrium requires no · 否 selection, so strong selection would break it. The other three are required. · 平衡要求没有选择,所以强选择会打破它。其余三条是必需的。
Hardy-Weinberg is an idealized baseline, not a description of real life. Almost no real population meets all five conditions perfectly. Its value is as a null model: differences from it reveal that evolution is happening.
哈迪-温伯格是一个理想化的基线,不是对真实生活的描述。几乎没有真实的种群能完美地满足全部五个条件。它的价值在于作为一个零模型:与它的差异揭示出进化正在发生。
Finding a hidden allele frequency:
- Suppose $9\%$ of a population shows a recessive trait, so $q^2 = 0.09$.
- Then $q = \sqrt{0.09} = 0.3$, and $p = 1 - 0.3 = 0.7$.
- Now you can predict the carriers: $2pq = 2(0.7)(0.3) = 0.42$, or $42\%$.
求一个隐藏的等位基因频率:
- 假设一个种群中 $9\%$ 显示隐性性状,所以 $q^2 = 0.09$。
- 那么 $q = \sqrt{0.09} = 0.3$,而 $p = 1 - 0.3 = 0.7$。
- 现在你能预测携带者:$2pq = 2(0.7)(0.3) = 0.42$,即 $42\%$。
Hardy-Weinberg equilibrium is a non-evolving baseline where allele frequencies stay constant, described by $p^2 + 2pq + q^2 = 1$. It holds only under five conditions: no selection, no migration, no mutation, random mating, and a large population. Real populations differ from it — and those differences reveal evolution.
哈迪-温伯格平衡是一个不进化的基线,等位基因频率保持不变,由 $p^2 + 2pq + q^2 = 1$ 描述。它只在五个条件下成立:没有选择、没有迁移、没有突变、随机交配和大种群。真实的种群与它有差异——而那些差异揭示了进化。