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17. Selection and Evolution

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  1. 17.1 Variation

    1. • Phenotypic variation: genetic factors, environmental factors, or combination

    2. • Discontinuous vs continuous variation

    3. • Genetic basis of discontinuous and continuous variation

    4. • t-test to compare means of two samples

  2. 17.2 Natural and Artificial Selection

    1. • Natural selection: populations produce many offspring competing for resources; best adapted survive to reproduce

    2. • Environmental factors as forces of natural selection: stabilising, disruptive, directional

    3. • Effects on allele frequencies: selection, founder effect, genetic drift (including bottleneck effect)

    4. • Bacterial antibiotic resistance as natural selection example

    5. • Hardy-Weinberg principle: calculate allele and genotype frequencies, conditions for application

    6. • Principles of selective breeding (artificial selection)

    7. • Selective breeding examples: - Disease resistance in wheat and rice - Inbreeding and hybridisation in maize - Improving milk yield in dairy cattle

  3. 17.3 Evolution

    1. 17.3.1Evolution through gene pool change

      • Theory of evolution: formation of new species from pre-existing species over time through gene pool changes

    2. 17.3.2DNA evidence for evolution

      • DNA sequence data showing evolutionary relationships

    3. 17.3.3Speciation through genetic isolation

      • Speciation through genetic isolation: - Geographical separation (allopatric speciation) - Ecological and behavioural separation (sympatric speciation)