GCSE WJEC Biology: Natural Selection Key Points | GCSE WJEC 生物：自然选择 考点精讲

📚 GCSE WJEC Biology: Natural Selection Key Points | GCSE WJEC 生物：自然选择 考点精讲

Natural selection is one of the most important ideas in biology and a core topic in your GCSE WJEC exam. It explains how populations become better adapted to their environment over generations. This guide breaks down every key point you need, from Darwin’s observations to antibiotic resistance, in a clear bilingual format designed to help you revise effectively.

自然选择是生物学中最重要的概念之一，也是你 GCSE WJEC 考试的核心课题。它解释了种群如何经过世代更替变得更能适应环境。本指南以清晰的双语形式，从达尔文的观察到抗生素耐药性，逐项分解你需要掌握的每一个考点，助你高效复习。

1. Introduction to Natural Selection | 自然选择概论

Natural selection is the evolutionary process by which organisms that are best adapted to their environment are more likely to survive, reproduce, and pass on advantageous alleles to the next generation.

自然选择是一种进化过程，在此过程中，最适应环境的生物更有可能存活、繁殖，并将有利的等位基因传递给下一代。

This concept, independently proposed by Charles Darwin and Alfred Russel Wallace, forms the cornerstone of modern biology.

这一概念由查尔斯·达尔文和阿尔弗雷德·拉塞尔·华莱士各自独立提出，构成了现代生物学的基石。

Natural selection acts on phenotypic variation within a population, gradually shifting the frequency of alleles across generations.

自然选择作用于种群内的表型变异，逐渐改变等位基因在代际间的频率。

2. Darwin’s Observations and Theory | 达尔文的观察与理论

During his voyage on HMS Beagle, Darwin observed striking variations among species on the Galapagos Islands, most famously the beaks of finches adapted to different diets.

在贝格尔号航行期间，达尔文观察到加拉帕戈斯群岛上物种间的显著变异，最著名的例子是适应不同食性的雀鸟喙形。

He noted that each island had finches with beak shapes suited to available food, suggesting that a common ancestor had diversified through natural selection.

他注意到每个岛屿上的雀鸟喙形都适应当地可得的食物，这表明一个共同祖先通过自然选择发生了多样化。

Darwin also studied artificial selection in domestic animals and plants, which helped him formulate his theory.

达尔文还研究了家养动植物的人工选择，这帮助他构建了自己的理论。

3. Variation: The Raw Material | 变异：自然选择的原材料

All populations exhibit genetic variation, which arises mainly through mutation and the random assortment of alleles during sexual reproduction.

所有种群都存在遗传变异，该变异主要来源于突变以及有性生殖过程中等位基因的随机分配。

Without variation, natural selection could not occur because there would be no differences in traits for the environment to act upon.

如果没有变异，自然选择就无法发生，因为没有可供环境作用的不同性状。

Variation can be continuous

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