Evolution, natural selection, and genetic drift

Connect inheritance to selection, drift, gene flow, adaptation, species formation, and evidence of shared ancestry.

Prerequisite: High-school biology and arithmetic. Genetics and probability are explained as needed. Eleven lessons build from allele counts and inheritance to population mechanisms, adaptation, speciation, evolutionary trees, and a resistance-evidence audit. Six interactive experiments and 22 worked exercises distinguish model predictions from observations about real populations.

Lessons

1. 1

   Identify evolutionary change

   Populations inherit variation and change across generations. An individual changing during life is a different process.

2. 2

   Connect inheritance to population variation

   Segregation transmits variants; dominance describes a phenotype relationship, not an allele’s fate.

3. 3

   Explain where new variation comes from

   Mutation creates variants; recombination and transfer alter how variants are distributed.

4. 4

   Derive natural selection from reproductive differences

   Heritable variants change frequency when they contribute unequally to later generations.

5. 5

   Understand genetic drift in finite populations

   Chance sampling changes frequencies even when variants have equal expected reproductive success.

6. 6

   Track migration and gene flow

   Movement changes allele frequencies when migrants contribute genes to the recipient population.

7. 7

   Use Hardy-Weinberg as a reference model

   Allele frequency and genotype frequency are related but can change differently.

8. 8

   Explain adaptation without assuming perfection

   Selection can produce useful traits, but trade-offs, history, and changing conditions limit what evolves.

9. 9

   Explain how populations become distinct lineages

   Speciation involves reduced genetic exchange and divergence; a geographic split alone is not enough.

10. 10

    Read evolutionary trees as ancestry hypotheses

    Branching relationships matter; tip order, visual proximity, and a ladder of progress do not.

11. 11

    Audit an evolutionary explanation

    Combine mechanisms and evidence without mistaking a plausible model for an established history.