Study Notes
Natural selection is a process where individuals with advantageous traits are more likely to survive and reproduce, leading to changes in the population over time. Variation — differences among individuals in a population. Example: Height, skin color, and blood group in humans. Mutation — the original source of genetic variation, creating new alleles. Example: A mutation can lead to antibiotic resistance in bacteria. Adaptation — characteristics that make an individual suited to its environment. Example: The long neck of a giraffe for reaching high leaves. Overproduction — species produce more offspring than the environment can support. Example: Southern ground hornbill raises one fledgling every three years. Differential survival and reproduction — better-adapted individuals are more likely to survive and reproduce. Example: Birds with beak shapes suited to available food sources. Allele frequency — the proportion of different alleles in a population changes over generations. Example: Beneficial alleles become more common due to natural selection.
Exam Tips
Key Definitions to Remember
- Variation: Differences among individuals in a population.
- Mutation: The original source of genetic variation.
- Adaptation: Characteristics that make an individual suited to its environment.
- Overproduction: Producing more offspring than the environment can support.
- Differential survival and reproduction: Better-adapted individuals are more likely to survive and reproduce.
Common Confusions
- Not all variations are beneficial; some can be neutral or detrimental.
- Acquired characteristics during an individual's lifetime are not inherited.
Typical Exam Questions
- What is natural selection? Natural selection is the process where individuals with advantageous traits are more likely to survive and reproduce.
- How does mutation contribute to variation? Mutation creates new alleles, increasing genetic diversity.
- Why is variation important for natural selection? Variation provides the raw material for natural selection to act upon.
What Examiners Usually Test
- Understanding of how natural selection leads to evolution.
- Examples of adaptations and their significance.
- The role of genetic variation in populations.