Metabolic and functional characterization of effects of developmental temperature in Drosophila melanogaster

Abstract

The ability of ectotherms to respond to changes in their thermal environment through plastic mechanisms is central to their adaptive capability. However, we still lack knowledge on the physiological and functional responses by which ectotherms acclimate to temperatures during development, and in particular, how physiological stress at extreme temperatures may counteract beneficial acclimation responses at benign temperatures. We exposed Drosophila melanogaster to 10 developmental temperatures covering their entire permissible temperature range. We obtained metabolic profiles and reaction norms for several functional traits: egg-to-adult viability, developmental time, and heat and cold tolerance. Females were more heat tolerant than males, whereas no sexual dimorphism was found in cold tolerance. A group of metabolites, mainly free amino acids, had linear reaction norms. Several energy-carrying molecules, as well as some sugars, showed distinct inverted U-shaped norms of reaction across the thermal range, resulting in a positive correlation between metabolite intensities and egg-to-adult viability. At extreme temperatures, low levels of these metabolites were interpreted as a response characteristic of costs of homeostatic perturbations. Our results provide novel insights into a range of metabolites reported to be central for the acclimation response and suggest several new candidate metabolites. Low and high temperatures result in different adaptive physiological responses, but they also have commonalities likely to be a result of the failure to compensate for the physiological stress. We suggest that the regulation of metabolites that are tightly connected to the performance curve is important for the ability of ectotherms to cope with variation in temperature.

Adjusting to climate: Acclimation, adaptation and developmental plasticity in physiological traits of a tropical rainforest lizard

“…That we should find acclimation in many of our traits is not surprising: acclimation of thermal physiology is commonly observed in a wide diversity of vertebrate and invertebrate terrestrial ectotherms (e.g. Kaufmann & Bennett 1989;Seebacher et al 2015;Schou et al 2017). Consistent with these previous studies, however, the magnitude of change in CT max through acclimation and/or among laboratory-bred individuals is less than for CT min (Fig.…”

A simple genetic basis of adaptation to a novel thermal environment results in complex metabolic rewiring in Drosophila

“…Additionally, higher CO 2 production in hot-evolved flies is consistent with increasing O 2 consumption associated with decreased AMPK activity (Johnson et al 2010). Further insights into this counter-intuitive pattern of CO 2 consumption comes from a metabolomic analysis of D. melanogaster under a wide range of developmental temperatures (Schou et al 2017). At extreme temperatures the flies were depleted for sugars and energy metabolites (NAD+, NADP+ and AMP), which is attributed to their inability to maintain cellular homeostasis.…”

Environmental variation partitioned into separate heritable components

“…We chose a linear fit because previous studies have shown that the relationship between CT min and developmental temperature is linear (Schou et al. ), and because linear norm‐of‐reaction analysis is the most commonly used in studies of phenotypic plasticity (Valladares et al. ).…”

“…1A). We chose a linear fit because previous studies have shown that the relationship between CT min and developmental temperature is linear (Schou et al 2017b), and because linear norm-of-reaction analysis is the most commonly used in studies of phenotypic plasticity (Valladares et al 2006). The variation of the plastic response (V v.plast ) was computed as the standard error of the regression coefficient ( Fig.…”