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Metabolic rate is canalized in the face of variable life history and nutritional environment
Author(s) -
Clark Rebecca M.,
Zera Anthony J.,
Behmer Spencer T.
Publication year - 2016
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1111/1365-2435.12574
Subject(s) - biology , fecundity , respiration , nutrient , cricket , organism , respiration rate , respiratory exchange ratio , carbohydrate metabolism , glycogen , life history theory , metabolism , ecology , life history , botany , biochemistry , endocrinology , population , paleontology , demography , heart rate , sociology , blood pressure
Summary Despite its central importance in organismal physiology, we have poor understanding of how metabolic rate is influenced by two key factors – food nutritional content and an organism's physiological characteristics. We examined how variation in nutrients and physiological aspects of life history affect standard metabolic rate in Gryllus firmus cricket morphs that differ dramatically in flight capability and early‐age fecundity. Newly moulted female morphs were fed one of 13 diets that differed in concentrations of protein and carbohydrate. Carbon dioxide production, respiratory exchange ratios (RERs), nutrient intake and mass and lipid levels were measured. CO 2 production and RERs increased to a similar degree in both morphs as food macronutrient content increased. In contrast, no difference in whole‐organism O 2 consumption was observed across the protein–carbohydrate landscape or between morphs. Both morphs similarly increased food intake as nutrient concentration – particularly protein – decreased, but differed in mass and lipid gains, across the diets. Modulation of the substrate used for respiration coupled with compensating aspects of morph‐specific metabolism appears to buffer the effects of variable nutrient intake and life history on standard metabolic rate. That is, respiration rate can be highly canalized in the face of dramatic variation in both the external nutritional environment and internal aspects of intermediary metabolism.