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Intrapopulation Variation in the Body Size at Metamorphosis and Timing of Metamorphosis in the Bullfrog, Rana Catesbeiana
Author(s) -
Collins James P.
Publication year - 1979
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1936611
Subject(s) - metamorphosis , bullfrog , larva , biology , population , ecology , amphibian , rana , zoology , demography , anatomy , sociology
Variation in body size at metamorphosis and the time of metamorphosis were studied for 3 yr in a population of bullfrogs at the E. S. George Reserve, Michigan, USA. The size at metamorphosis and the week of metamorphosis were positively related through the 1972 activity season and the last half of the 1973 activity season. During the first half of 1973 and all of 1974 there was no significant relationship between size and metamorphosis and time of metamorphosis. The data suggest that the 1971 larval year class transformed during 1972 and 1973, the 1972 year class during 1973 and 1974 and the 1973 year class during 1974. Variation in length of the larval period and body size at metamorphosis varied with density of conspecifics and time of oviposition during spring and early summer. Data for the Michigan population of frogs are consistent with predictions derived from a model of amphibian metamorphosis proposed by Wilbur and Collins (1973). A review of the literature indicates that length of the larval period among populations of bullfrogs in the United States is negatively correlated with mean length of the frost—free period.