Biology 1201A Lecture Notes - Lecture 16: Allele Frequency, Genotype Frequency, Directional Selection
4 Jan 2018
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Chapter 16. 3d: natural selection shapes genetic variability by favouring some traits over others. Natural selection- process by which such beneficial, heritable traits become more common in subsequent generations. Thus, natural selection violates a condition of the hardy-weinberg. Equilibrium and causes allele and genotype frequencies to differ from those predicted by the model. Although natural selection can change allele frequencies, it is the phenotype of an individual organism, rather than any particular allele, that is successful or not. Relative fitness- the number of surviving offspring that an individual produces compared with the number left by others in the population. Differences in the relative success of individuals are the essence of natural selection. Directional selection: (common: when individuals near one end of the phenotype spectrum have the highest relative fitness. Shifts a trait away from the existing mean and toward the favoured extreme.
