📚 The Darwin–Wallace Theory of Evolution by Natural Selection | 达尔文–华莱士自然选择进化论
The Darwin–Wallace theory of evolution by natural selection explains how populations change over generations. It was proposed independently by Charles Darwin and Alfred Russel Wallace and forms the foundation of modern evolutionary biology.
达尔文–华莱士自然选择进化论解释了种群如何逐代发生变化。该理论由查尔斯·达尔文和阿尔弗雷德·拉塞尔·华莱士分别独立提出，是现代进化生物学的基石。
1. Historical Background | 历史背景
Before Darwin and Wallace, most naturalists believed that species were fixed and specially created. However, fossils and global exploration revealed extinct forms and geographical variation that challenged this static view.
在达尔文和华莱士之前，大多数博物学家认为物种是固定不变、被特殊创造出来的。然而，化石和全球考察所揭示的灭绝类型和地理变异，动摇了这种静态观点。
Darwin’s voyage on HMS Beagle from 1831 to 1836 and Wallace’s expeditions in the Malay Archipelago provided key field observations. Both naturalists read Thomas Malthus’s essay on population growth, which shaped their thinking about competition and limited resources.
达尔文于1831年至1836年乘坐小猎犬号航行，华莱士则在马来群岛进行考察，这些经历提供了关键的野外观察。两位博物学家都阅读了托马斯·马尔萨斯关于人口增长的文章，这影响了他们关于竞争与有限资源的思想。
2. The Two Key Observations | 两个关键观察
Natural selection rests on two fundamental observations. First, organisms produce more offspring than can possibly survive. Second, individuals within a population vary in their traits.
自然选择建立在两个基本观察之上。第一，生物产生的后代数量超过了实际能够存活的数量。第二，种群内个体之间的性状存在差异。
Many of these variations are heritable, even though the exact mechanism of inheritance was not understood in Darwin and Wallace’s time. This heritable variation is essential for natural selection to cause evolutionary change.
许多变异是可遗传的，尽管在达尔文和华莱士的时代，人们还不了解具体的遗传机制。这种可遗传变异是自然选择引起进化变化的必要条件。
3. Overproduction of Offspring | 后代过度繁殖
All species tend to produce far more offspring than are needed to replace the parent generation. A single fish may release thousands of eggs, and a single oak tree may produce millions of acorns, yet population sizes often remain roughly stable over time.
所有物种都会产生远多于替代亲代所需数量的后代。一条鱼可以产下数千枚卵，一棵橡树可以产生数百万颗橡果，但种群数量通常在一段时间内大致保持稳定。
This potential for exponential growth is checked by limited resources such as food, water, shelter and mates. The mismatch between reproductive potential and available resources creates a struggle for existence.
这种指数增长的潜力受到食物、水、栖息地和配偶等有限资源的制约。繁殖潜力与可用资源之间的不匹配，导致了生存竞争。
4. Variation Within Populations | 种群内变异
Individuals in a population differ in size, colour, speed, disease resistance and many other traits. Some of this variation is genetic and can be passed from parents to offspring; other variation may be due to the environment and is not heritable.
种群中的个体在大小、颜色、速度、抗病性以及许多其他性状上存在差异。其中部分变异是遗传性的，可以从亲代传给子代；另一部分变异可能由环境引起，并不遗传。
Only heritable variation can be acted on directly by natural selection. Environmental variation may affect survival but cannot cause an evolutionary response in the population unless it is linked to genetic differences.
自然选择只能直接作用于可遗传变异。环境引起的变异虽然可能影响存活，但如果不与遗传差异关联，就无法在种群中引起进化响应。
5. Struggle for Existence | 生存竞争
Because resources are limited, individuals must compete for survival. Competition may be between members of the same species for food, territory or mates, or between different species that share similar needs.
由于资源有限，个体必须为生存而竞争。竞争可能发生在同一物种成员之间，例如争夺食物、领地或配偶，也可能发生在具有相似需求的不同物种之间。
Predation, disease and unfavourable environmental conditions also remove many individuals before they can reproduce. This means that only a fraction of each generation survives to pass on its genes.
捕食、疾病和不利环境条件也会使许多个体在繁殖前死亡。这意味着每一代中只有一部分个体能够存活并传递其基因。
6. Survival of the Fittest | 适者生存
Individuals with traits that are better suited to their environment are more likely to survive and reproduce than individuals with less favourable traits. In biology, ‘fitness’ means reproductive success, not simply physical strength or speed.
具有更适应环境性状的个体，比性状不太有利的个体更有可能生存和繁殖。在生物学中，“适合度”指繁殖成功，而不仅仅是体力或速度。
Differential survival and reproduction lead to the best-adapted variants contributing more offspring to the next generation. For example, antibiotic-resistant bacteria survive antibiotic treatment and reproduce, increasing the frequency of resistance in the bacterial population.
差异化生存和繁殖使得适应力最强的变异为下一代贡献更多后代。例如，抗生素耐药细菌在抗生素治疗中存活并繁殖，从而提高了耐药性在细菌种群中的频率。
| Stage | Explanation | 中文解释 |
|---|---|---|
| 1 | Overproduction of offspring | 后代过度繁殖 |
| 2 | Heritable variation among individuals | 个体间存在可遗传变异 |
| 3 | Competition for limited resources | 争夺有限资源 |
| 4 | Differential survival and reproduction | 差异化生存与繁殖 |
| 5 | Increase in frequency of advantageous traits | 有利性状频率增加 |
7. Inheritance of Favourable Traits | 有利性状的遗传
Favourable traits are passed from parents to offspring more frequently because those parents reproduce more successfully. Over generations, the frequency of advantageous alleles or traits in the population increases.
有利性状更频繁地从亲代传给子代，因为具有这些性状的亲代繁殖更成功。经过多代之后，有利等位基因或性状在种群中的频率逐渐增加。
This process is the essential link between ecology and heredity. Natural selection can only shape a population if parents transmit the traits that gave them a reproductive advantage.
这一过程是生态学与遗传学之间的关键联系。只有当亲代能够传递那些赋予其繁殖优势的性状时，自然选择才能塑造种群。
8. Accumulation of Change and Speciation | 变异积累与物种形成
Natural selection acts on individual organisms, but its evolutionary effects accumulate in populations over many generations. Small selective advantages, when repeated across thousands or millions of generations, can produce major changes.
自然选择作用于生物个体，但其进化效应会在许多世代中积累于种群。微小的选择优势经过数千代或数百万代的反复作用，可以产生巨大的变化。
If populations become isolated and experience different selection pressures, they may diverge so much that they can no longer interbreed. This reproductive isolation is the basis of speciation.
如果种群被隔离并经历不同的选择压力，它们可能会分化到无法再相互交配的程度。这种生殖隔离是物种形成的基础。
Darwin described this gradual process as ‘descent with modification’: species change over time and share common ancestors.
达尔文将这种渐进过程描述为“带有修饰的遗传”：物种随时间发生变化，并拥有共同祖先。
9. Wallace’s Independent Contribution | 华莱士的独立贡献
Alfred Russel Wallace reached very similar conclusions while studying the fauna of Southeast Asia. He recognised that species varied geographically and that natural selection could explain adaptation.
阿尔弗雷德·拉塞尔·华莱士在研究东南亚动物群时得出了非常相似的结论。他认识到物种在地理上存在变异，并认为自然选择可以解释适应现象。
In 1858, Darwin and Wallace presented a joint paper to the Linnean Society in London. Darwin then published On the Origin of Species in 1859, making the theory widely known.
1858年，达尔文和华莱士向伦敦林奈学会宣读了一篇联合论文。随后达尔文于1859年出版了《物种起源》，使该理论广为人知。
Wallace’s later work on biogeography and warning coloration provided further support for evolution by natural selection. His name remains permanently linked with Darwin’s because both men independently discovered the same mechanism.
华莱士后来在生物地理学和警戒色方面的研究，进一步支持了自然选择进化论。由于两人独立发现了同一机制，华莱士的名字始终与达尔文联系在一起。
10. Evidence Supporting the Theory | 支持理论的证据
The fossil record shows transitional forms and a sequence of change over geological time. Fossil evidence is consistent with descent with modification from common ancestors.
化石记录显示了过渡形态和地质时间上的变化顺序。化石证据与来自共同祖先的“带有修饰的遗传”相一致。
Biogeography shows that related species tend to be clustered geographically. Wallace’s Line, for example, separates Asian and Australasian fauna and reflects evolutionary history rather than current climate alone.
生物地理学表明，亲缘关系相近的物种往往在地理上聚集分布。例如，华莱士线分隔了亚洲和澳大利亚动物群，反映了进化历史而非仅仅由当前气候决定。
Artificial selection in crops and domestic animals demonstrates that selective breeding can produce dramatic changes in a relatively short time. Modern molecular biology also reveals shared DNA sequences and genetic variation within populations.
农作物和家养动物中的人工选择表明，选择性育种可以在较短时间内产生显著变化。现代分子生物学也揭示了种群中的共享DNA序列和遗传变异。
| Evidence | What it shows | 中文说明 |
|---|---|---|
| Fossil record | Change over time and transitional forms | 显示随时间变化和过渡形态 |
| Biogeography | Geographical distribution reflects common ancestry | 地理分布反映共同祖先 |
| Artificial selection | Selection can alter trait frequencies rapidly | 选择可迅速改变性状频率 |
| Molecular biology | Shared DNA sequences and genetic variation | 共享DNA序列和遗传变异 |
11. Modern Evolutionary Synthesis | 现代综合进化论
In the 20th century, Mendelian genetics was combined with Darwin’s theory to explain how variation arises and is inherited. This is called the modern evolutionary synthesis.
20世纪，孟德尔遗传学与达尔文理论相结合，解释了变异如何产生和遗传。这被称为现代综合进化论。
Mutations introduce new alleles, and gene flow, genetic drift and natural selection all affect allele frequencies in populations. Among these processes, natural selection is the only one that consistently produces adaptation to the environment.
突变引入新的等位基因，基因流、遗传漂变和自然选择都会影响种群中的等位基因频率。在这些过程中，自然选择是唯一能持续产生环境适应性的机制。
The modern synthesis answered a major weakness in Darwin’s original theory: the lack of a known mechanism of inheritance. It also clarified that natural selection acts on phenotypes but changes genotype frequencies over generations.
现代综合论弥补了达尔文原理论的一个重大缺陷：缺乏已知的遗传机制。它还阐明了自然选择作用于表现型，但在世代间改变基因型频率。
12. Common Misconceptions and Exam Tips | 常见误区与应试技巧
A common mistake is to say that ‘individuals evolve’ or that organisms choose to adapt. Individuals do not evolve; populations evolve over generations as allele frequencies change.
一个常见错误是说“个体在进化”或生物选择去适应环境。个体不会进化；种群通过等位基因频率的改变在世代间发生进化。
Natural selection has no foresight. It acts on existing variation and cannot create a trait just because it would be useful. Beneficial mutations arise by chance, and selection then increases their frequency.
自然选择没有预见性。它作用于已有的变异，不会仅仅因为某个性状有用就创造该性状。有利突变是偶然产生的，随后选择提高其频率。
In exams, always link the chain: selection pressure → heritable variation → differential survival and reproduction → increased frequency of advantageous alleles → adaptation. Use named examples such as antibiotic resistance in bacteria to support your answer.
考试中务必按以下链条作答：选择压力 → 可遗传变异 → 差异化生存与繁殖 → 有利等位基因频率增加 → 适应性。使用具体实例，如细菌的抗生素耐药性，来支持你的答案。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导