Temperature Effects on Energy Metabolism in Banded and Unbanded Morphs of the Snail Cepaea hortensis Müll

Energy metabolism (oxygen consumption) in acclimated juvenile yellow banded and unbanded Cepaea hortensis Müll. was measured at 5°, 10°, 15°, 20°, and 25° C with Englemann respirometers. Metabolic rates were also measured after abrupt temperature changes from 5° to 20° and from 25° to 10° C. Energy metabolism in the two morphs was significantly different at 5° and 20° C. The metabolism/temperature curve in the banded morph was relatively flat with reduced regulating power at 20° C. The yellow unbanded form had a lower metabolism at 5° C, but between 15° and 25° C the curve was flat and indicated good regulating ability. A sudden decrease in experimental temperature gave significant response in both morphs. The effect of abrupt temperature increase was significant only in unbanded snails. Banded and unbanded snails thus displayed different adaptation strategies. Differential heating because of different pigmentation is discussed. The increase in metabolic rate with increased temperature was highest in the yellow unbanded morph. The effects were small and probably overridden by the influences of acclimation and behavior. The use of energetic parameters in ecological genetics is considered. It is suggested that the cohort producing most progeny with lowest energetic cost per energy unit of offspring is the better adapted to the local environment.