Natural Selection and Evolution
Discover how populations change over generations through natural selection, genetic drift, mutation, and migration. Evolution is the unifying principle connecting all of biology.
Learning Path
Food Webs and Energy Pyramids Poster
Visual guide to energy flow through ecosystems and the 10% transfer rule. See how natural selection shapes predator-prey relationships and drives population change.
Open →Hardy-Weinberg Equilibrium Calculator
Calculate allele and genotype frequencies, test populations for Hardy-Weinberg equilibrium with chi-square, and simulate evolutionary forces over generations.
Open →Hardy-Weinberg and Natural Selection Lab
Simulate allele frequency changes across generations under selection, drift, mutation, and migration. Test Hardy-Weinberg equilibrium with chi-square analysis.
Open →Key Concepts
The core principles of population genetics and evolution.
- Hardy-Weinberg: p^2 + 2pq + q^2 = 1
- p + q = 1 (allele frequencies)
- Selection favors higher-fitness variants
- Genetic drift: random change in small populations
- Speciation: reproductive isolation over time
More Resources
Tools
Labs
Worksheets
Cheat Sheets
Infographics
Explainers
Common Questions
What are the conditions for Hardy-Weinberg equilibrium?
A population is in Hardy-Weinberg equilibrium when there is no mutation, no gene flow, random mating, a large population size, and no natural selection. When these conditions hold, allele and genotype frequencies remain constant across generations.
How does natural selection differ from genetic drift?
Natural selection is non-random: heritable traits that increase reproductive success become more common over generations. Genetic drift is random: allele frequencies fluctuate by chance, and the effect is strongest in small populations.