Phenotypic flexibility of energetics in acclimated Siberian hamsters has a narrower scope in winter than in summer

Abstract

As photoperiod shortens with the approach of winter, small mammals should reduce their energy expenditure to survive periods of food limitation. However, within seasons, animals should balance their energy budgets as abiotic conditions change, sometimes unpredictably; cold spells should increase heat production, while warm spells should do the opposite. Therefore, we addressed specific questions about the possible interactions between seasonal acclimatization and the intra-seasonal phenotypic flexibility of metabolic rate. We hypothesized that phenotypic flexibility in small mammals differs seasonally and is greater in summer than in winter, and predicted that seasonal adjustments in energetics, which are driven by photoperiod, overwhelm the influence of variations in the thermal environment. We measured body mass, basal metabolic rate (BMR), facultative non-shivering thermogenesis (fNST), body temperature, and calculated minimum thermal conductance in Siberian hamsters Phodopus sungorus. Animals were acclimated to winter-like, and then to summer-like conditions and, within each season, were exposed twice, for 3 weeks to 10, 20 or 28 °C. We used differences between values measured after these short acclimation periods as a measure of the scope of phenotypic flexibility. After winter acclimation, hamsters were lighter, had lower whole animal BMR, higher fNST than in summer, and developed heterothermy. After these short acclimations to the above-mentioned temperatures, hamsters showed reversible changes in BMR and fNST; however, these traits were less flexible in winter than in summer. We conclude that seasonal acclimation affects hamster responses to intra-seasonal variations in the thermal environment. We argue that understanding seasonal changes in phenotypic flexibility is crucial for predicting the biological consequences of global climate changes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00360-016-0959-3) contains supplementary material, which is available to authorized users.

Phenotypic flexibility in heat production and heat loss in response to thermal and hydric acclimation in the zebra finch, a small arid-zone passerine

“…Such phenotypic flexibility may be crucial in response to changes in environmental conditions, especially in the face of present and predicted climate change (present study; Cooper et al 2020b;Noakes and McKechnie 2019;Noakes et al 2016;Oswald et al 2018;Tieleman et al 2002bTieleman et al , 2002aTieleman 2000, 2002). Possibly, this phenotypic flexibility may also undergo seasonal changes as it was shown in mammals (Boratyński et al 2016a(Boratyński et al , 2017b. Also, since thermal history may affect flexibility of energy metabolism (Barcelo et al 2009), we cannot exclude that acclimation to high T a 's in summer may additionally facilitate flexible adjustments of thermoregulatory traits.…”

Individual‐based analysis of hair corticosterone reveals factors influencing chronic stress in the American pika

“…Being a small alpine mammal that does not hibernate, the American pika may be especially dependent on a fine‐tuned metabolic rate, given that smaller animals would be disproportionately affected by low temperatures (Moyer‐Horner et al., ). As a case in point, Boratyński, Jefimow, and Wojciechowski () found that both the basal metabolic rate and nonshivering thermogenesis in Siberian hamsters were highly plastic during the summer months to meet local thermal conditions. If such patterns generalize to the current study, the elevational pattern of GC reported here may represent the metabolic plasticity of pikas to local thermal conditions.…”

Difference in plasticity of resting metabolic rate – the proximate explanation to different niche breadth in sympatricFicedulaflycatchers

“…For examples, guppies ( Poecilia reticulata ) change their RMR in response to predators (Handelsman et al., ), mouse ( Mus musculus ) RMR fluctuates over the course of pregnancy (Speakman & McQueenie, ), and generally, birds’ RMR changes in response to cool, seasonal temperatures (McKechnie, ). In addition, experimental studies in hamsters ( Phodopus sungorus ) have demonstrated marked differences in metabolic rate in response to short‐term differences in ambient temperature (Boratyński, Jefimow, & Wojciechowski, , ). Thus, there is ample evidence suggesting that plasticity in metabolic rate allows organism to quickly adjust to short‐term changes in the environment.…”