3.7 Speciation

3.7 Genetics, populations, evolution and ecosystems
3.7.3 Genetic variation and adaptation
3.7.3.5 Evolution may lead to speciation

• Carefully sequenced lesson exploring how new species arise through genetic and reproductive isolation
• Explicit teaching of key concepts: species, gene flow, reproductive isolation, and selection pressures
• Clear distinction between:
• Allopatric speciation (geographical isolation)
• Sympatric speciation (no physical barrier)
• Step-by-step modelling of how allele frequencies change over time, leading to divergence and inability to interbreed
• Strong focus on mechanisms of reproductive isolation:
• behavioural
• mechanical
• seasonal
• Active retrieval embedded throughout (MWBs, prior knowledge checks, structured FNT approach)
• Students apply knowledge to real-world contexts (e.g. rock pocket mice, fish, mole rats) to explain evolutionary divergence
• Exam practice integrated: extended-response questions developing structured explanations of speciation
• Addresses key misconceptions (e.g. speciation happens quickly, barriers must be large, similar appearance = same species)
• Develops disciplinary thinking: sequencing biological processes and explaining evolution over time