Changing allele frequencies · 改变等位基因频率
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| founder effect/ˈfaʊndə ɪˈfekt/ | 奠基者效应 | diàn jī zhě xiào yìng |
| genetic drift/dʒɪˈnetɪk drɪft/ | 遗传漂变 | yí chuán piāo biàn |
| bottleneck effect/ˈbɒtəlnek ɪˈfekt/ | 瓶颈效应 | píng jǐng xiào yìng |
| Hardy–Weinberg principle/ˈhɑːdi ˈwaɪnbɜːɡ ˈprɪnsɪpl/ | 哈迪-温伯格原理 | hā dí - wēn bó gé yuán lǐ |
Evolution by the numbers
- Natural selection isn't the only thing that changes a gene pool.
- Chance events can shift allele frequencies too.
- And we can calculate them with Hardy–Weinberg.
用数字看演化
- 自然选择不是改变基因库的唯一东西。
- 偶然事件也能改变等位基因频率。
- 而且我们能用 哈代-温伯格(Hardy–Weinberg) 计算它们。
Allele frequency change lab · 等位基因频率变化实验
See how a population can move from chance or selection to changed allele frequency. · 观察种群如何从偶然事件或选择转变为等位基因频率的改变。
A change in the allele frequencies of a population over generations is called . · 种群在几代内发生的等位基因频率改变称为。
Selection and genetic drift change allele frequencies — that is evolution at the genetic level. · 选择和遗传漂变改变等位基因频率——即遗传水平上的进化。
Founder, drift and bottleneck
- founder effect 奠基者效应 — a few individuals start a new population, so they carry only some of the original alleles.
- genetic drift 遗传漂变 — in a small population, allele frequencies change by chance each generation.
- bottleneck effect 瓶颈效应 — a sudden fall in population size leaves few survivors, reducing the variety of alleles.
The bottleneck effect reduces genetic variety
奠基者、漂变和瓶颈
- 奠基者效应(founder effect)——少数个体开始一个新群体,所以它们只携带 一些 原始的等位基因。
- 遗传漂变(genetic drift)——在一个 小 群体中,等位基因频率每一代因 偶然 而改变。
- 瓶颈效应(bottleneck effect)——群体大小突然下降留下很少的幸存者,减少 等位基因的多样性。
瓶颈效应减少遗传多样性
The founder effect happens when: · 奠基者效应发生在：
The few founders carry only a sample of the original gene pool, so the new population differs. · 少数奠基者只携带原始基因库的一个样本，因此新种群有所不同。
A population bottleneck reduces genetic variety because: · 种群瓶颈减少了遗传多样性，因为：
Few survivors carry only some alleles, so the recovered population has less variety. · 少数幸存者只携带部分等位基因，因此恢复后的种群多样性较低。
Match each cause of changing allele frequency to its description. · 将每个改变等位基因频率的原因与其描述匹配。
Selection is non-random (by fitness); drift, founder and bottleneck effects are random changes, strongest in small populations. · 选择是非随机的（基于适应性）；漂变、奠基者和瓶颈效应是随机变化，在小种群中最强。
Antibiotic resistance
- A chance mutation makes a few bacteria resistant to an antibiotic.
- The antibiotic kills the non-resistant ones; the resistant ones survive and reproduce.
- So resistance spreads — natural selection in action.
抗生素抗性
- 一个偶然的 突变 使少数细菌对一种抗生素 有抗性。
- 抗生素杀死没有抗性的;有抗性的 存活并繁殖。
- 所以抗性传播——运作中的自然选择。
Antibiotic resistance is an example of natural selection because: · 抗生素耐药性是自然选择的例子，因为：
A chance mutation gives resistance; the antibiotic selects for it, so resistant bacteria increase. · 偶然突变赋予耐药性；抗生素对其进行选择，使耐药细菌数量增加。
Hardy–Weinberg
- The Hardy–Weinberg principle 哈迪-温伯格原理 lets you calculate allele and genotype frequencies in a population.
- It only holds when: a large population, random mating, and no mutation, migration or natural selection.
哈代-温伯格
- 哈代-温伯格原理(Hardy–Weinberg principle) 让你计算一个群体中的 等位基因 和 基因型 频率。
- 它只在以下情况成立:一个 大 群体、随机 交配,以及 没有 突变、迁移或自然选择。
The Hardy–Weinberg principle only holds true when there is: · 哈迪-温伯格平衡原则仅在以下情况下成立：
Hardy–Weinberg assumes a large, randomly mating population with no mutation, migration or selection. · 哈迪-温伯格假设大种群、随机交配，且无突变、迁移或选择。
In a population the recessive phenotype (q²) makes up 0.04 of individuals. What is the recessive allele frequency, q? · 在一个种群中，隐性表型（q²）占个体的0.04。隐性等位基因频率q是多少？
q² = 0.04, so q = √0.04 = 0.2. (Then p = 1 − q = 0.8.) · q² = 0.04，所以 q = √0.04 = 0.2。（然后 p = 1 − q = 0.8。）
You've got it
- founder effect (few start a new population), genetic drift (chance in small populations), bottleneck (disaster cuts variety)
- antibiotic resistance spreads by natural selection (mutation → survivors reproduce)
- Hardy–Weinberg calculates allele/genotype frequencies — needs a large population, random mating, no mutation/migration/selection
你掌握了
- 奠基者效应(少数开始一个新群体)、遗传漂变(小群体中的偶然)、瓶颈(灾难削减多样性)
- 抗生素抗性 通过自然选择传播(突变 → 幸存者繁殖)
- 哈代-温伯格 计算等位基因/基因型频率——需要一个大群体、随机交配、没有突变/迁移/选择