Metabolic rate is canalized in the face of variable life history and nutritional environment

Abstract

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. CO2 production and RERs increased to a similar degree in both morphs as food macronutrient content increased. In contrast, no difference in whole‐organism O2 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.

Revisiting GUD: An empirical test of the size-dependency of patch departure behaviour

“…In addition to size, operational temperature is well known to influence metabolic rates in accordance with the Boltzmann-Arrhenius dependence [ 22 , 86 , 87 ]. The metabolic dependence of patch exploitation efficiency observed here implies that temperature variations may have an effect on resource patch exploitation efficiency by systematically affecting metabolic rates and individual resource requirements [ 22 , 86 ].…”

Artificial selection for odor-guided behavior in Drosophila reveals changes in food consumption

“…It is possible that correlated changes in food consumption are indeed associated with changes in the metabolic traits measured here, but not at levels sufficient for detection. Alternatively, potential differences in other metabolic traits not measured in this study, such as metabolic rate, could underlie the observed differences in food consumption [ 63 ]. In the case of dry mass, a difference among lines was only observed in the 4MP selection regime despite changes in both food consumption and odor-guided behavioral responses being observed in both 4EG and 4MP selection regimes.…”

Artificial selection on chill-coma recovery time in Drosophila melanogaster: Direct and correlated responses to selection

“…For example, 57 correlations have been observed when selection drives an increased heat tolerance which is 58 positively correlated to an increase in cold tolerance, but selection to tolerance to cold does not 59 necessarily carry a correlated response of tolerance to heat (Bubliy and Loeschcke 2005). 60 Furthermore, studies have examined correlations between stress metrics such as cold tolerance 61 and starvation resistance (Bubliy and Loeschcke 2005, Le Bourg 2013, Le Bourg and Massou 2015, Sinclair et al 2007, Scharf et al 2016, cold selection and heat tolerance capacity (Anderson et al 2005, Kristensen et al 2007, diet manipulations and metabolic mechanisms (Clark et al 2015, Harshman et al 1999, Sisodia et al 2015, response to hypoxia and cold tolerance (Benasayah-Meszaros et al 2015, Boardman et al 2011, Boardman et al 2015, and 5 cold survivorship, desiccation resistance, and body size (Benoit et al 2009, Gantz and Lee 2015, Jumbo-Lucioni et al 2010, Terhazaz et al 2015.…”