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The Effect of Temperature on Reproduction in Some Morphs of the Landsnail Cepaea nemoralis (L.)
Vol. 21, No. 1 (Mar., 1967), pp. 117-129
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2406745
Page Count: 13
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In constant temperature rooms the influence of temperature on reproduction was tested in the polymorphic landsnail Cepaea nemoralis (L). Snails from different natural populations showed significant differences in mortality, mating frequency, oviposition frequency and clutch size although all snails were of about the same age and had lived under nearly identical circumstances in the laboratory for about one year. This suggests that these differences may have a genetic basis. Some of these differences are affected by temperature. Oviposition frequency and mortality were found to differ at 20C but not at 12C. As was expected from earlier observations under natural conditions, the influence of temperature on oviposition frequency in yellow banded snails was about twice that in red banded ones. Yellow unbanded snails produced significantly more clutches than either yellow banded or red unbanded ones at both temperatures. Yellow unbanded snails also produced significantly more clutches than red banded ones at 20C, but not at 12C. Quite unexpectedly no influence of temperature on mean clutch size could be found. The earlier observations that clutch size was positively correlated with temperature at oviposition time and that clutches were relatively large after a period of warm dry weather must be explained by some cause other than temperature. If, however, the morphs are considered separately, there is some indication that temperature has some influence. At 20C yellow banded and red unbanded snails produced smaller clutches than did red banded and yellow unbanded ones and at 12C the situation seems to be the reverse. Significant positive correlations were found between snail shell size (diameter) and oviposition frequency, and also between size and clutch size.
Evolution © 1967 Society for the Study of Evolution