Energy metabolism, heart rate and physiological differentiation in the pulmonate gastropod Cornu aspersum

Abstract

We explored differences in metabolic rates of the introduced snail Cornu aspersum collected from three distant coastal locations across a 1300 km latitudinal range in Chile and raised under common-garden conditions. We measured two proxies of metabolic rate: heart rate (f H ) and CO 2 production (standard metabolic rate, SMR) in a flow-through respirometry system. Although both variables were significantly correlated (r 2 = 0.49), suggesting that f H could be a predictor of SMR, the relationship between f H and SMR and also the CO 2 pulse (SMR/f H ) varied across populations. Whereas SMR suggested an increase in energy metabolism towards high latitudes, supporting metabolic cold adaptation, f H indicated no trend (northern and southern populations exhibited the largest values). Our results suggest that, in invertebrates, energy metabolism cannot be inferred from heart rate. Our results show metabolic differentiation towards increased metabolic heat production in the southern location, warranting further analyses of functional differentiation in these introduced populations. © The Author 2013. Published by Oxford University Press on behalf of The Malacological Society of London, all rights reserved.