These peculiar discoveries represent more than biological curiosities, the biologists say, constituting the first clear demonstration that living organisms arise not only through the direct read-out of some genetic recipe, but also through more subtle and mysterious processes of competition between growing body parts for resources.
According to the scientists, this competition, first suggested almost 150 years ago by Charles Darwin in Origin of Species, offers a highly cautionary lesson for scientists and laypersons alike who believe that genes are the direct blueprint for all aspects of a living organism, whether it be dung beetles or humans.
Such competition or resource tradeoffs between growing parts, in fact, may make inherited changes in some traits or structures appear genetic when they are not, say the biologists.
The researchers, Professor of Zoology Fred Nijhout and postdoctoral fellow Douglas Emlen, published their findings in the March 31 issue of the Proceedings of the National Academy of Sciences. Their work was supported by the Duke University Morphometrics Laboratory and the National Science Foundation.
In their experiments with butterflies, the scientists performed tiny incisions in caterpillars to remove one or both of the small fleshy discs that would develop into the hind wings once the caterpillars underwent metamorphosis. When the butterflies emerged, they had abnormally enlarged front wings.
In one set of experiments with the scarab dung beetles, the researchers
treated male beetle larvae with a hormone known to decrease size of the horns --
which
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Contact: Dennis Meredith
Dennis@dukenews.duke.edu
919-681-8054
Duke University
30-Mar-1998