Meeting Abstract

58.3  Jan. 6  Causal association between organ masses and aerobic metabolism in the diamondback water snake BOBACK, S.M.*; SECOR, S.M.; University of Alabama sboback@ua.edu

Organ mass variation has been interpreted to be an underlying source of inter-individual variation in metabolic rate. We addressed this hypothesis by exploring the relationship between organ mass and aerobic metabolism in the diamondback water snake (Nerodia rhombifer). We measured from over 300 water snakes (7 � 1930 g) standard metabolic rate (SMR), maximum metabolic rate (VO_2max), and the wet and dry masses of all organs including skin, muscle, and bone. Dried organ masses (Log10) scaled to body mass (Log10) with exponents ranging between 0.80 and 1.30. Mass residuals from logarithmic regressions were positively correlated between most organ pairs. Scaling exponents of SMR and VO_2max were statistically equivalent and their mass residuals were significantly correlated. SMR residuals were correlated with dry mass residuals of the heart, lung, liver, stomach, small intestine, large intestine, kidneys, bone, and skin, whereas VO_2max residuals were correlated with mass residuals of the heart, liver, stomach, bone, and skin. Incorporated into a multiple regression, heart, liver, stomach, and kidney masses explained 40% of the variation in SMR and 12% of the variation in VO_2max. Apparently, in the diamondback water snake variation in organ mass and consequently organ metabolism underlies inter-individual variation in aerobic performance.