PCB 4674 Lecture Notes - Lecture 13: The Bell Curve, Gall Wasp, Stabilizing Selection
29 Oct 2016
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Weis and abrahamson (1986) fly study: female fly injects egg into goldenrod bud. Plant produces a gall to protect its tissues fly larvae feeds on plant within the gall flies possesses genetic variation that influences gall size: two predators prey on fly larvae while still in gall. Wasp inserts her own egg which feeds on fly larvae. Disruptive selection: smith (1993) african finches, two beak sizes large and crushing. Small and dexterous: large beak feed on larger harder seeds. Small beak feed on smaller seeds requiring delicate handling: intermediate beak not able to feed efficiently on either kind of seed, note that there is also an element of stabilizing selection superimposed upon the overall disruptive pattern. Because extreme values of the phenotypes are also eliminated. Except for individuals with extremely long bills: this illustrates an important point it is entirely possible for two or even all three modes of selection to be occurring simultaneously to some extent.
