Evolution and Biodiversity
Core concepts
Understand natural selection (variation, heritability, differential reproduction), adaptation, and evidence for evolution (fossils, comparative anatomy, molecular data). Know mechanisms of change: mutation, gene flow, genetic drift, natural selection. Distinguish homologous vs. analogous structures, convergent vs. divergent evolution, and speciation (allopatric vs. sympatric). Understand classification and biodiversity.
Traps in questions
- Natural selection acts on phenotypes, not directly on genotypes; populations evolve, individuals do not.
- Homologous structures share ancestry; analogous structures share function only.
- Genetic drift is random and strongest in small populations.
- Mutation is the ultimate source of new alleles; selection only sorts existing variation.
Worked example / rule of thumb
Antibiotic resistance: random mutations → some bacteria survive → they reproduce → resistant population. Rule of thumb: variation → selection → differential reproduction → change in allele frequency. Always state which mechanism is acting and whether it is random (drift) or directional (selection).