Genetic variation refers to the differences in DNA sequences among individuals within a population. It’s the foundation of evolution by natural selection, providing the raw material for adaptation and species diversity. In IB Biology, understanding how genetic variation arises is essential to explain how populations evolve and respond to environmental pressures.
Quick Start Checklist for IB Biology Students
- Define genetic variation and explain its biological significance
- Learn the three main sources: mutation, meiosis, and sexual reproduction
- Understand how allele frequency changes drive evolution
- Practice data-based questions on population genetics
- Review these concepts using RevisionDojo’s IB Biology learning platform
1. Mutations: The Original Source of Variation
A mutation is a permanent change in the DNA sequence of an organism. Mutations can occur spontaneously during DNA replication or be induced by environmental factors such as radiation and chemicals.
- Point mutations change one base in a gene, sometimes altering a protein’s function.
- Insertions or deletions can shift the genetic reading frame.
- Chromosomal mutations may involve larger-scale structural changes.
While many mutations are neutral or harmful, some are beneficial and provide a selective advantage. Over generations, these beneficial mutations can spread throughout a population, driving evolutionary adaptation.
2. Meiosis: Creating New Combinations of Alleles
During meiosis, gametes (sperm and eggs) are formed, and this process introduces variation through:
- Homologous chromosomes exchange segments, creating new allele combinations.
