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Concepts from Lecture 22

Concepts from Lecture 22 - Naturalselection...

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Natural selection Absolute fitness‐ a measure or reproductive success. In the example the number of seeds per plant. Relative fitness – the contribution of an individual phenotype to the next generation relative to the contribution of other phenotypes. In our example we measured relative to the most successful phenotype – red flowers. Natural selection can be directional, disruptive, and stabilizing. Directional selection is the favoring of individuals at one particular end of the phenotypic range (remember the bell curve, individuals at one of the curve are favored). So over time the phenotypic curve will shift in the direction that is favored. Example include antibiotic and pesticide resistance (resistant ones do better!). Disruptive selection is the favoring of individuals at both ends of the phenotypic range – so the phenotypic curve will change over time so that the intermediete individuals will be less abundant and the curve will look like two peaks at each end of the extreme. Examples include
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