Biology 1002B Lecture 11: Outcomes of Cycle 6
30 Jun 2016
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Chap 18 why it matters, 18. 1: difference between quantitative and qualitative variation. Quantitative variation: individuals differ in small, incremental ways. Width of the curve is proportional to the variability. Men describes the average value of the trait in the population. Qualitative variation: traits that exist in two or more discrete states, and intermediate forms are often absent. Polymorphism: the existence of discrete variants of a character. (many form) Snail shells are polymorphic in background color, no. of stripes: sources of phenotypic variation, and which of these is/are heritable. Genetic variation: only genetic variation is heritable, affected by evolutionary change. Depend on individual"s phenotype, rather than its genotype, that is successful or not. Natural selection operates on the phenotype, not genotype. Also, it operates on the whole phenotype, not just one gene at a time. Note: same genotypes sometime exhibit different phenotypes: meaning of directional, stabilizing, disruptive selection.
