Natural and artificial selection

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

1. **Variation:** Individuals within a population show genetic variation (due to mutation, meiosis, random fertilisation) in their phenotypes. Some variations are heritable.
2. **Overproduction:** Organisms typically produce more offspring than can survive to reproductive age.
3. **Struggle for Existence:** Resources are limited, leading to competition for food, mates, space, and avoidance of predators or disease.
4. **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.