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Seasonality in Biological Rhythms in Scandinavian brown Bears

Biological rhythms, such as rhythms in activity and body temperature, are usually highly synchronized and entrained by environmental conditions, such as photoperiod. However, how the expression of these rhythms changes during hibernation, when the perception of environmental cues is limited, has not...

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Autores principales: Thiel, Alexandra, Giroud, Sylvain, Hertel, Anne G., Friebe, Andrea, Devineau, Olivier, Fuchs, Boris, Blanc, Stephane, Støen, Ole-Gunnar, Laske, Timothy G., Arnemo, Jon M., Evans, Alina L.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9118031/
https://www.ncbi.nlm.nih.gov/pubmed/35600291
http://dx.doi.org/10.3389/fphys.2022.785706
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author Thiel, Alexandra
Giroud, Sylvain
Hertel, Anne G.
Friebe, Andrea
Devineau, Olivier
Fuchs, Boris
Blanc, Stephane
Støen, Ole-Gunnar
Laske, Timothy G.
Arnemo, Jon M.
Evans, Alina L.
author_facet Thiel, Alexandra
Giroud, Sylvain
Hertel, Anne G.
Friebe, Andrea
Devineau, Olivier
Fuchs, Boris
Blanc, Stephane
Støen, Ole-Gunnar
Laske, Timothy G.
Arnemo, Jon M.
Evans, Alina L.
author_sort Thiel, Alexandra
collection PubMed
description Biological rhythms, such as rhythms in activity and body temperature, are usually highly synchronized and entrained by environmental conditions, such as photoperiod. However, how the expression of these rhythms changes during hibernation, when the perception of environmental cues is limited, has not yet been fully understood for all hibernators, especially in the wild. The brown bear (Ursus arctos) in Scandinavia lives in a highly seasonal environment and adapts to harsh winter conditions by exhibiting hibernation, characterized by reduced metabolism and activity. In this study, we aimed to explore the expression of biological rhythms in activity, body temperature and heart rate of free-ranging brown bears over the annual cycle, including active, hibernation and the transition states around den entry and exit. We found that rhythms in physiology and activity are mostly synchronized and entrained by the light-dark cycle during the bears’ active state with predominantly diel and ultradian rhythms for body temperature, activity and heart rate. However, during hibernation, rhythms in body temperature and heart rate were considerably slowed down to infradian rhythms, influenced by the amount of snow in the denning area, whereas rhythms in activity remained diel. Rhythms in the transition states when bears prepared for entering or coming out of hibernation state displayed a combination of infradian and diel rhythms, indicating the preparation of the body for the change in environmental conditions. These results reveal that brown bears adjust their biological rhythms to the seasonal environment they inhabit. Rhythms in physiology and activity show simultaneity during the active state but are partly disconnected from each other during hibernation, when bears are most sheltered from the environment.
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spelling pubmed-91180312022-05-20 Seasonality in Biological Rhythms in Scandinavian brown Bears Thiel, Alexandra Giroud, Sylvain Hertel, Anne G. Friebe, Andrea Devineau, Olivier Fuchs, Boris Blanc, Stephane Støen, Ole-Gunnar Laske, Timothy G. Arnemo, Jon M. Evans, Alina L. Front Physiol Physiology Biological rhythms, such as rhythms in activity and body temperature, are usually highly synchronized and entrained by environmental conditions, such as photoperiod. However, how the expression of these rhythms changes during hibernation, when the perception of environmental cues is limited, has not yet been fully understood for all hibernators, especially in the wild. The brown bear (Ursus arctos) in Scandinavia lives in a highly seasonal environment and adapts to harsh winter conditions by exhibiting hibernation, characterized by reduced metabolism and activity. In this study, we aimed to explore the expression of biological rhythms in activity, body temperature and heart rate of free-ranging brown bears over the annual cycle, including active, hibernation and the transition states around den entry and exit. We found that rhythms in physiology and activity are mostly synchronized and entrained by the light-dark cycle during the bears’ active state with predominantly diel and ultradian rhythms for body temperature, activity and heart rate. However, during hibernation, rhythms in body temperature and heart rate were considerably slowed down to infradian rhythms, influenced by the amount of snow in the denning area, whereas rhythms in activity remained diel. Rhythms in the transition states when bears prepared for entering or coming out of hibernation state displayed a combination of infradian and diel rhythms, indicating the preparation of the body for the change in environmental conditions. These results reveal that brown bears adjust their biological rhythms to the seasonal environment they inhabit. Rhythms in physiology and activity show simultaneity during the active state but are partly disconnected from each other during hibernation, when bears are most sheltered from the environment. Frontiers Media S.A. 2022-04-07 /pmc/articles/PMC9118031/ /pubmed/35600291 http://dx.doi.org/10.3389/fphys.2022.785706 Text en Copyright © 2022 Thiel, Giroud, Hertel, Friebe, Devineau, Fuchs, Blanc, Støen, Laske, Arnemo and Evans. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Physiology
Thiel, Alexandra
Giroud, Sylvain
Hertel, Anne G.
Friebe, Andrea
Devineau, Olivier
Fuchs, Boris
Blanc, Stephane
Støen, Ole-Gunnar
Laske, Timothy G.
Arnemo, Jon M.
Evans, Alina L.
Seasonality in Biological Rhythms in Scandinavian brown Bears
title Seasonality in Biological Rhythms in Scandinavian brown Bears
title_full Seasonality in Biological Rhythms in Scandinavian brown Bears
title_fullStr Seasonality in Biological Rhythms in Scandinavian brown Bears
title_full_unstemmed Seasonality in Biological Rhythms in Scandinavian brown Bears
title_short Seasonality in Biological Rhythms in Scandinavian brown Bears
title_sort seasonality in biological rhythms in scandinavian brown bears
topic Physiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9118031/
https://www.ncbi.nlm.nih.gov/pubmed/35600291
http://dx.doi.org/10.3389/fphys.2022.785706
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