What you’ll learn7 learning objectivesChoose one objective for a focused lesson, or study the complete topic.17.2.1Natural selection mechanism• Natural selection: populations produce many offspring competing for resources; best adapted survive to reproduceSyllabus objective17.2.2Stabilising, disruptive and directional selection• Environmental factors as forces of natural selection: stabilising, disruptive, directionalSyllabus objective17.2.3Effects on allele frequencies• Effects on allele frequencies: selection, founder effect, genetic drift (including bottleneck effect)Syllabus objective17.2.4Antibiotic resistance and selection• Bacterial antibiotic resistance as natural selection exampleSyllabus objective17.2.5Hardy-Weinberg principle• Hardy-Weinberg principle: calculate allele and genotype frequencies, conditions for applicationSyllabus objective17.2.6Selective breeding principles• Principles of selective breeding (artificial selection)Syllabus objective17.2.7Selective breeding examples• Selective breeding examples:- Disease resistance in wheat and rice- Inbreeding and hybridisation in maize- Improving milk yield in dairy cattleSyllabus objective