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What Is Natural Selection?
Meta title: What Is Natural Selection in IB Biology?
Meta description: Discover how natural selection drives evolution and why it’s one of the most important concepts in IB Biology. Learn how to master this topic with RevisionDojo.
Natural selection is the process by which organisms with traits better suited to their environment are more likely to survive, reproduce, and pass on those traits to the next generation. Over time, this leads to evolutionary change, shaping species and increasing their fitness in specific environments. In IB Biology, natural selection is a core topic that explains how diversity and adaptation arise in the natural world.
Quick Start Checklist for IB Biology Students
- Understand Charles Darwin’s theory of evolution by natural selection
- Learn key terms: variation, adaptation, fitness, and survival
- Be able to describe examples of evolution in real species
- Practice data-based questions involving allele frequency changes
- Strengthen your understanding with RevisionDojo IB Biology study guides
How Natural Selection Works
Natural selection operates on genetic variation within populations. These variations arise through mutations, meiosis, and sexual reproduction, providing the raw material for evolution.
The process follows several key steps:
- Variation exists among individuals in a population.
- Competition occurs for limited resources such as food and space.
- Individuals with advantageous traits are more likely to survive and reproduce.
- Favorable traits are inherited by offspring and become more common in the population over time.
This continuous process results in populations that are better adapted to their environment — a principle central to the IB Biology Evolution and Biodiversity unit.
Examples of Natural Selection
- Peppered moths (Biston betularia): During the Industrial Revolution, dark-colored moths were more likely to survive against soot-darkened trees. When pollution decreased, lighter moths regained an advantage.
- Antibiotic resistance in bacteria: Bacteria that survive antibiotic treatment reproduce, passing on resistant genes — a real-world concern studied in both genetics and evolution.
- Darwin’s finches: On the Galápagos Islands, finches evolved different beak shapes to exploit specific food sources.
Each of these cases demonstrates adaptation, where species evolve traits that enhance survival and reproduction.
Why Natural Selection Is So Important
Natural selection explains the unity and diversity of life. It connects genetics, ecology, and evolution into one coherent framework. For IB students, understanding this mechanism provides the foundation for answering long-response questions that link inheritance, variation, and environmental pressures.
It also ties directly into biodiversity conservation, as understanding how species adapt helps predict how ecosystems might respond to environmental change. IB learners can explore case studies like antibiotic resistance or climate-driven migration patterns using RevisionDojo’s IB Biology course to reinforce understanding through real-world examples and IB-style assessments.
Revision Tips
- Memorize the four key principles of natural selection.
- Practice explaining evolution without invoking individual intent — emphasize population-level change.
- Use graph-based exam questions to describe how allele frequencies shift over time.
FAQs
What is the main idea of natural selection?
Natural selection explains how individuals with traits that provide a survival or reproductive advantage are more likely to pass those traits on, leading to evolution.
How does natural selection relate to adaptation?
Adaptation is the result of natural selection — advantageous traits become common because they improve fitness in a given environment.
Why is natural selection essential for IB Biology?
It’s a core concept that underpins genetics, evolution, and ecology. Understanding it helps students make connections across the syllabus and excel in essay-style questions.
