BIOL 1001 Chapter Notes - Chapter 3.4: Natural Experiment, Natural Selection
21 Jan 2017
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(cid:1007). (cid:1008)- case study #(cid:1006): why are beak size, beak shape. Finches beaks size, shape and body size vary amount individuals & beak morphology & body size vary among individuals. Beak size, beak shape and body size are traits with heritable variation. Plants that produced seeds died and 84% of medium ground finches disappeared due to starvation. Natural experiments allow researches to compare treatment groups created by unplanned change in conditions. Could test weather natural selection occurred by comparing the populations before & after drought. Survivors tended to have steeper beaks than the ones that died. Natural selection lead to an increase in beak depth. In one generation, natural selection lead to a measurable change in characteristics of the population. Alleles that lead to the development of deep beaks had increased in frequency in the population. Large beaks were an adaptation for cracking large fruits and seeds. Continued changes in environment, continued selection & continued evolution.
