Evolutionary Physiology
Credit: Wiki
Phenotypic Plasticity During Early Life
Credit: S. Giroud
Credit: S. Giroud
In fluctuating environments, the timing of reproduction is key for the reproductive success and survival of animal species. It is important that periods of gestation, birth and development of juveniles match optimal food availability in order to maximize chances of survival.
During summer time, the decline of ambient temperatures and food availability combined to poor food quality can overlap with the requirements for growth and development of juveniles. This is particularly observed in late-breeders, i.e. species reproducing and giving birth late in the reproductive season.
In the context of global change, the availability and the quality of trophic resources, in environments already fluctuating, are largely affected by unpredictable climatic events, whose frequency and intensity keeps increasing. Hence, it appears crucial to determine and characterize the phenotypic plasticity of the physiological responses of animal species, in particular during their early life stages, as well as the ecological and evolutionary consequences of such strategies, in response to large and rapid environmental fluctuations. In that regard, heterothermic species are particularly good models to study these adaptations, since juvenile heterotherms have to ensure both their growth and pre-hibernation fattening to survive their first winter already in hibernation.
This research program is oriented along two major axes: (1) the ontogenesis of energy-saving strategies of juvenile heterotherms, and (2) the processes of growth and development, according to the timing of reproduction and food availability and quality.
Within each axis, we aim to determine the physiological and behavioral mechanisms (from the whole-body level to the molecule), as well as the ecological and evolutionary consequences (from the individual to the population) of the phenotypic plasticity during early life stages. Specifically, energetic strategies conferring the highest flexibility to the individuals are likely to be conserved and spread among the populations.
The main collaborations for the development of this research line include Prof Caroline Gilbert (CNRS Brunoy, France), Dr Caroline Habold (CNRS Strasbourg, France), Dr Steve Smith (Vetmeduni Vienna), Prof Gerda Egger (Medical University Vienna), and Prof Andreas Nord (Lund University). This research is conducted on conducted on small species contrasting in their life history strategies.
The Phenology of Hibernation
Credit: C. Habold
Evolutionary causes and consequences of hibernation phenology
PhD thesis of Théo Constant at the Hubert Curien Pluridisciplinary Institute of the CNRS at Strasbourg, France [2019-2022]
This thesis aims to better understand the evolutionary causes and consequences of hibernation phenology. Théo's results suggest that hibernation phenology is explained by a trade-off between survival benefits of hibernating and benefits of remaining active for reproduction.
Using an interspecific approach, Théo demonstrated that longer hibernation duration was associated with increased longevity across 82 hibernating species. In contrast to these results, an intraspecific approach in the common hamster (Cricetus Cricetus) revealed that an increase in hibernation duration is instead associated with fast life history traits, i.e., short longevity and numerous offspring.
Théo's results on the same species further suggest that longevity of hibernators can be explained by the metabolic depression during hibernation and the ability of hibernators to elongate telomeres irrespective of the time of the year.
This thesis therefore opens new avenues in understanding the responses of hibernating species in the context of global change.