9700 · 17.2
Natural and artificial selection
Welcome to a crucial topic in evolution! **Natural selection** and **artificial selection** are two fundamental processes that drive changes in populations over time, leading to adaptation and the development of new varieties or breeds. While both involve a 'selection' process, the agent doing the selecting and the ultimate goal differ significantly. Understanding these distinctions is vital for Paper 4, where you'll often be asked to explain mechanisms and evaluate consequences. Key points align with **A-Level Notes** 9700 Biology chapter **17** (topic **17.2**).
Need to know
What you need to know
- **Variation:** Individuals within a population show genetic variation (due to mutation, meiosis, random fertilisation) in their phenotypes. Some variations are heritable.
- **Overproduction:** Organisms typically produce more offspring than can survive to reproductive age.
- **Struggle for Existence:** Resources are limited, leading to competition for food, mates, space, and avoidance of predators or disease.
- **Differential Survival and Reproduction:** Individuals with advantageous heritable traits are better adapted to the environment. They are more likely to survive the struggle, reproduce successfully, and pass on those advantageous alleles.
- **Inheritance:** The offspring inherit the advantageous alleles, increasing their frequency in the gene pool of the next generation.
- **Adaptation:** Over many generations, the proportion of individuals with these advantageous traits increases, leading to a population that is better adapted to its environment.
Explanation
Natural and artificial selection
- **Variation:** Individuals within a population show genetic variation (due to mutation, meiosis, random fertilisation) in their phenotypes. Some variations are heritable.
- **Overproduction:** Organisms typically produce more offspring than can survive to reproductive age.
- **Struggle for Existence:** Resources are limited, leading to competition for food, mates, space, and avoidance of predators or disease.
- **Differential Survival and Reproduction:** Individuals with advantageous heritable traits are better adapted to the environment. They are more likely to survive the struggle, reproduce successfully, and pass on those advantageous alleles.