. Elements of ecology. Ecology. Harmful Effects 319 ther growth of the colony is prevented. Organisms continuing to Hve in the same medium tend to change or to "condition" it. Condition- ing of flour by laboratory populations of the flour beetle Tribolium confusiwi has been shown to cause reduced fecundity, extended dura- tion of metamorphosis, and increased mortality (Park, 1941). The same kinds of harmful changes are brought about by overcrowding under natural conditions. In some situations aquatic animals may aggregate to such an extent as to exhaust the oxygen supply; else- where
. Elements of ecology. Ecology. Harmful Effects 319 ther growth of the colony is prevented. Organisms continuing to Hve in the same medium tend to change or to "condition" it. Condition- ing of flour by laboratory populations of the flour beetle Tribolium confusiwi has been shown to cause reduced fecundity, extended dura- tion of metamorphosis, and increased mortality (Park, 1941). The same kinds of harmful changes are brought about by overcrowding under natural conditions. In some situations aquatic animals may aggregate to such an extent as to exhaust the oxygen supply; else- where they may exhaust the food supply, produce harmful metabo- lites, or displace one another mechanically. Of several hundred oyster larvae originally setting on an old shell or other small object, only a few will find sufficient space to develop into full-sized oysters; all the others will eventually be killed by crowding. Where com- petition for space is keen, oysters grow in a long slender form, un- desirable for the market. Oystermen in cultivating their beds com-. 10 20 30 40 50 60 70 80 90 Mean flies per bottle Fio. Curve showing decrease in rate of reproduction in Drosophila as cul- tures become more crowded. (Pearl and Parker, 1922.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Clarke, George L. (George Leonard), 1905-. New York, Wiley
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Keywords: ., bookcentury1900, bookpublishernewyorkwiley, booksubjectecology
