Physiology and adaptation

Stress and reproduction in Arctic birds

Global warming is more pronounced in the Arctic than anywhere else on the planet. The effects are direct, such as reduced sea ice or Arctic ocean temperature, or indirect, such as the arrival of new prey or predators. We are studying the cascading effects of these changes (by measuring stress or reproductive hormones) on the body condition, migration and reproduction of seabirds. Similar work is being conducted by the team on black-legged kittiwakes in Svalbard and common eiders in Nunavut. These two species can live more than 20 years and decide whether or not to breed in a given year. Our studies show that the reproductive decision is closely related to stress physiology in both species. The main environmental stresses encountered are the quality and availability of prey and winter storms. Finally, the impact of a stress may persist over time and affect migration or body condition.

Ecophysiology and Biogeography

Current climate change is having major effects on biodiversity with local extinctions and range changes. In order to understand these phenomena, it is necessary to elucidate the proximal mechanisms involved. Our work on snakes has revealed strong contrasts in physiological adaptations between species according to their global biogeography. Thus, cold-climate species have a higher metabolic rate than warm-zone species and more pronounced water losses. They are therefore exposed to higher energy expenditure in the face of rising temperatures. This approach has also been validated on a finer scale in France by studying the Pelias viper. We have modelled the distribution of the species by combining correlative and physiological approaches and highlighted the role of the Massif Central as a “climatic refuge”.

Adaptation to marine life in reptiles

The evolutionary transition to marine life in mammals, birds and reptiles provides insight into how the marine environment has shaped these organisms in terms of morphology, hydrodynamics and apnoea capacities. The salinity of seawater has a dehydrating power for these organisms, which must excrete excess salt through specialized kidneys in mammals and a specialized organ: the salt gland in birds and reptiles. Despite these adaptations to salinity, we have shown in marine snakes that access to fresh water is vital for these organisms. Moreover, biogeographic analyses suggest that oceanic salinity has been a real lock to evolutionary transitions to the marine environment where only certain species have been able to adapt to this environment. These transitions likely took place in particular environments where salinity was relatively low and highly variable. 808 characters spaces not_included