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Genetics of Body Size and Related Characters. II. Satellite Characters Associated with Body Size in Mice
John W. MacArthur
The American Naturalist
Vol. 78, No. 776 (May - Jun., 1944), pp. 224-237
Stable URL: http://www.jstor.org/stable/2458253
Page Count: 14
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Small and large races of mice produced from one stock by eight generations of selection for body size alone, came to differ strikingly and significantly, not only in body size, but unexpectedly in many other characters and traits as well (behavior, hair colors, relative length of the appendages and litter size). The large race, for instance, has certain distinguishing coat colors (brown, dilute, etc.); is more docile and inactive; has comparatively shorter ears, feet and tail; and bears many more young in a litter. The coat colors are such as are controlled by genes, either known to exert pleiotropic growth-accelerating effects, or probably fixed by chance drift. Behavior differences may be associated with metabolic levels. Appendages are proportionately small because they grow less rapidly than the body in the last stages of growth. Large litters are due to superovulation in the large race, evidently regulated by the gonadotropic hormone of the anterior pituitary. Litter size and length of appendages appear to be dependent, like satellites, upon body size as the central and dominating member of a complex of correlated characters, with a common developmental basis in growth. Differences between the mouse races in litter size or length of appendages are determined, not by special fertility factors or ear-length genes, etc., but, in great part at least, by the same common and general multiple size or growth rate factors that control body size. Several applications to general biological problems are suggested.
The American Naturalist © 1944 The University of Chicago Press