Unformatted text preview: The change occurred at a time when increased pollution from coal fired factories darkened the trees. By 1895, 98% of the moths in Manchester were the dark form. Hypothesis A hypothesis is an explanation of an observation. In 1896, J. W. Tutt hypothesized that bird predation was responsible for the increase in abundance of the dark form of the moth. He reasoned that birds had difficulty seeing the dark form on the dark trees; the moths were camouflaged and survived better. In clean areas, the trees were covered with lichens, making the pale form more difficult for birds to see. In the early 1800s, the trees were light and the light form were more difficult to see. A hypothesis must be testable, and if false, it must be falsifiable....
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- Fall '10
- Biology, dark form, Descriptive Science and Experimental Science, light form