Course review
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Learning objective
• Natural selection is the mechanism driving evolutionary change • It acts on heritable variation and can produce adaptation, speciation, and biodiversity
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Learning objective
• Mutation creates new alleles, especially when germ-line mutations are inherited • Meiosis and random fertilization create new combinations of existing alleles
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Learning objective
• Overproduction of offspring leads to high mortality in limited environments • Competition for food, space, mates, and other resources promotes selection
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Learning objective
• Abiotic factors can act as density-independent selection pressures • Temperature, drought, light, salinity, and pH can favour different variants
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Learning objective
• Individuals vary in adaptation, survival, and reproductive success • Fitness means passing alleles to offspring in a particular environment
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Learning objective
• Natural selection causes evolution only if traits are heritable • Acquired characteristics are not inherited through DNA base sequences
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Learning objective
• Sexual selection favours traits that increase mate choice or mating competition success • Displays, ornaments, and behaviours such as birds-of-paradise plumage can be selected
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Learning objective
• Selection can be modelled by experimentally controlling selection pressures • Endler's guppy experiments test predation pressure, colour pattern, and mating success
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Learning objective
• A gene pool contains all genes and alleles in an interbreeding population • Evolution can be measured as changes in allele frequencies over generations
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Learning objective
• Allele frequency is the proportion of a specific allele in the gene pool • Geographically isolated populations can diverge in allele frequencies
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Learning objective
• Natural selection increases alleles linked to higher survival or reproduction • Neo-Darwinism combines Mendelian genetics, mutation, recombination, and Darwinian selection
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Learning objective
• Directional selection favours one extreme phenotype • Stabilizing favours intermediate phenotypes; disruptive favours both extremes
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Learning objective
• Hardy-Weinberg equations calculate allele and genotype frequencies in equilibrium • Use p + q = 1 and p² + 2pq + q² = 1 for two alleles
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Learning objective
• Equilibrium requires large population, random mating, no selection, mutation, migration, or drift • Deviations from expected frequencies indicate evolutionary forces acting
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Learning objective
• Artificial selection deliberately chooses parents with desired heritable traits • Crop, livestock, and pet breeding show directed change; resistance can arise unintentionally
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