Plasticity of the ontegenesis of energy savings mechanisms in heterotherm mammals

 
Garden dormice are kept in species appropriate conditions at FIWI. (Photo K. Svadlenak/ Vetmeduni Vienna)
Garden dormouse in the FIWI enclosure
 
The garden dormouse (Eliomys quercinus) is a rodent of the family of the Gliridae. The garden dormouse's main habitat is the forest, though it can also be found in fruit-growing regions. (Photo K. Svadlenak / Vetmeduni Vienna)
In the last few decades, this species, which is native to Europe, has suffered drastic declines and reductions in area, which is why the IUCN lists the garden dormouse as a kind of "near-threatened" species. (Photo K. Svadlenak / Vetmeduni Vienna)
Juvenile garden dormice in the nest
Old illustration of a garden dormouse from the Pocket atlas of the mammals of France, Romanesque Switzerland and Belgium: with their description, customs and organization followed by an overall study on mammals (Foto René Martin/Wikimedia Commons)
Old illustration of a garden dormouse from a french atlas 1

In the context of global change and increasing frequency of unpredictable climate events, there is growing interest in how well physiological flexibility can buffer organisms from environmental hazards. One key metabolic constraint imposed by environmental fluctuations is food shortage. Heterothermy (daily torpor and hibernation) allows energy savings in response to reduced food availability. But flexibility of heterothermy has almost exclusively been investigated in adult animals. How do conditions of heterothermy expression in juveniles during their development shape the efficiency of torpor? Are individuals born under harsh conditions better prepared to use torpor later in life? Is there a multigenerational epigenetic transmission of heterothermy regulation? Heterothermic juveniles are under strong selective pressure to grow and fatten fast before their first winter, which is critical for their survival.

A team around Dr. Sylvain Giroud is studying the developmental sequences of torpor in a hibernator, the garden dormouse (Eliomys quercinus, Rodents), which uses both winter hibernation and daily or prolonged torpor before winter. The team is investigating how exposure to food shortage during growth shapes the use of torpor during adulthood (caloric restriction vs. reference diet; Objective 1).

Social thermoregulation is a widespread energy-saving strategy that is complementary to torpor. Only few species use both strategies, but we expect their combination to permit individuals to maximise energy savings in relation to their environmental constraints. A major advantage of social thermoregulation resides in the simultaneous possibility to minimize energy expenditure while  maintaining a relatively high body temperature (Tb), which is necessary for sufficient growth. Huddling is also believed to allow a reduction in energy costs for the rewarming phase from a torpid state. Periodic phases of arousals from torpor are particularly demanding in terms of energy and are associated with greater levels of oxidative stress, impacting on the animal’s somatic maintenance. Minimising these costs could be advantageous for young individuals raised in groups, on both a short-term and a long-term basis (Objective 2).

In the final part of the project, the team is going to test whether individual differences in torpor use could have an epigenetic basis that can potentially be transmitted to the next generation (Objective 3). This is a fundamental mystery in the regulation of phenotypic flexibility: can the phenotype of descendants be optimized by parents to improve offspring performance in response to future food shortage?

The project is a sub-project of the research programme "Phenotypic flexibility during earlife life".

 

Duration

01 September 2018-31 May 2022

 

Science grant

FWF logo 2

FWF 3 Project P31577


 

Scientific contact at FIWI

Dr. Sylvain Giroud, Research Institute of Wildlife Ecology, Vetmeduni Vienna

T. +43 (1)  25077-7135

Email Sylvain Giroud


 
Sylvain Giroud, scientific leader of the project
Photo of Sylvain Giroud 4

 

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