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41     phenology of wing color
DHJanzen100634.jpg
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A closer view of image DHJanzen100634.jpg above allows inspection to reveal that the two clutches of sibs are not perfectly synchronized with each other. The clutch across the upper part of the board produced rust-red males for 1-2 days longer into the rainy season than did the cluch beneath them. This kind of variation offers the raw materials for selection for changes in phenology of the population. The upper clutch also produced a few rust-orange males substantially into the rainy season, while the lower clutch produced none at all. Again, this is the kind of variation that natural selection can operate on.
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