scholarly journals Photoperiodic induction without light-mediated circadian entrainment in a High Arctic resident bird

2020 ◽  
Vol 223 (16) ◽  
pp. jeb220699 ◽  
Author(s):  
Daniel Appenroth ◽  
Vebjørn J. Melum ◽  
Alexander C. West ◽  
Hugues Dardente ◽  
David G. Hazlerigg ◽  
...  
Keyword(s):  
Activity Patterns ◽  
High Arctic ◽  
Gonadal Development ◽  
Photoperiodic Response ◽  
Day Length ◽  
The Arctic ◽  
Constant Darkness ◽  
Polar Regions ◽  
Natural Photoperiod ◽  
Lagopus Muta

ABSTRACTOrganisms use changes in photoperiod to anticipate and exploit favourable conditions in a seasonal environment. While species living at temperate latitudes receive day length information as a year-round input, species living in the Arctic may spend as much as two-thirds of the year without experiencing dawn or dusk. This suggests that specialised mechanisms may be required to maintain seasonal synchrony in polar regions. Svalbard ptarmigan (Lagopus muta hyperborea) are resident at 74–81°N latitude. They spend winter in constant darkness (DD) and summer in constant light (LL); extreme photoperiodic conditions under which they do not display overt circadian rhythms. Here, we explored how Arctic adaptation in circadian biology affects photoperiodic time measurement in captive Svalbard ptarmigan. For this purpose, DD-adapted birds, showing no circadian behaviour, either remained in prolonged DD, were transferred into a simulated natural photoperiod (SNP) or were transferred directly into LL. Birds transferred from DD to LL exhibited a strong photoperiodic response in terms of activation of the hypothalamic thyrotropin-mediated photoperiodic response pathway. This was assayed through expression of the Eya3, Tshβ and deiodinase genes, as well as gonadal development. While transfer to SNP established synchronous diurnal activity patterns, activity in birds transferred from DD to LL showed no evidence of circadian rhythmicity. These data show that the Svalbard ptarmigan does not require circadian entrainment to develop a photoperiodic response involving conserved molecular elements found in temperate species. Further studies are required to define how exactly Arctic adaptation modifies seasonal timer mechanisms.

scholarly journals Photoperiodic induction without light-mediated circadian entrainment in a high arctic resident bird

2020 ◽  
Author(s):  
Daniel Appenroth ◽  
Vebjørn J. Melum ◽  
Alexander C. West ◽  
Hugues Dardente ◽  
David G. Hazlerigg ◽  
...  
Keyword(s):  
Activity Patterns ◽  
High Arctic ◽  
Gonadal Development ◽  
Photoperiodic Response ◽  
Day Length ◽  
The Arctic ◽  
Constant Light ◽  
Constant Darkness ◽  
Polar Regions ◽  
Lagopus Muta

AbstractOrganisms use changes in photoperiod to anticipate and exploit favourable conditions in a seasonal environment. While species living at temperate latitudes receive day length information as a year-round input, species living in the Arctic may spend as much as two-thirds of the year without experiencing dawn or dusk. This suggests that specialised mechanisms may be required to maintain seasonal synchrony in polar regions.Svalbard ptarmigan (Lagopus muta hyperborea) are resident at 74-81° north latitude. They spend winter in constant darkness (DD) and summer in constant light (LL); extreme photoperiodic conditions under which they do not display overt circadian rhythms.Here we explored how arctic adaptation in circadian biology affects photoperiodic time measurement in captive Svalbard ptarmigan. For this purpose, DD-adapted birds, showing no circadian behaviour, either remained in prolonged DD, were transferred into a simulated natural photoperiod (SNP) or were transferred directly into LL. Birds transferred from DD to LL exhibited a strong photoperiodic response in terms of activation of the hypothalamic thyrotropin-mediated photoperiodic response pathway. This was assayed through expression of the Eya3, Tshβ and deiodinase genes, as well as gonadal development. While transfer to SNP established synchronous diurnal activity patterns, activity in birds transferred from DD to LL showed no evidence of circadian rhythmicity.These data show that the Svalbard ptarmigan does not require circadian entrainment to develop a photoperiodic response involving conserved molecular elements found in temperate species. Further studies are required to define how exactly arctic adaptation modifies seasonal timer mechanisms.Summary statementSvalbard ptarmigan show photoperiodic responses when transferred from constant darkness to constant light without circadian entrainment.

scholarly journals Body Temperature and Activity Rhythms Under Different Photoperiods in High Arctic Svalbard ptarmigan (Lagopus muta hyperborea)

2021 ◽  
Vol 12 ◽  
Author(s):  
Daniel Appenroth ◽  
Andreas Nord ◽  
David G. Hazlerigg ◽  
Gabriela C. Wagner
Keyword(s):  
Body Temperature ◽  
Circadian Rhythms ◽  
Core Body Temperature ◽  
High Arctic ◽  
The Arctic ◽  
Constant Darkness ◽  
Polar Regions ◽  
Circadian Control ◽  
Polar Day ◽  
Lagopus Muta

Organisms use circadian rhythms to anticipate and exploit daily environmental oscillations. While circadian rhythms are of clear importance for inhabitants of tropic and temperate latitudes, its role for permanent residents of the polar regions is less well understood. The high Arctic Svalbard ptarmigan shows behavioral rhythmicity in presence of light-dark cycles but is arrhythmic during the polar day and polar night. This has been suggested to be an adaptation to the unique light environment of the Arctic. In this study, we examined regulatory aspects of the circadian control system in the Svalbard ptarmigan by recording core body temperature (Tb) alongside locomotor activity in captive birds under different photoperiods. We show that Tb and activity are rhythmic with a 24-h period under short (SP; L:D 6:18) and long photoperiod (LP; L:D 16:8). Under constant light and constant darkness, rhythmicity in Tb attenuates and activity shows signs of ultradian rhythmicity. Birds under SP also showed a rise in Tb preceding the light-on signal and any rise in activity, which proves that the light-on signal can be anticipated, most likely by a circadian system.

scholarly journals Adaptive value of circadian rhythms in High Arctic Svalbard ptarmigan

2020 ◽  
Author(s):  
Daniel Appenroth ◽  
Gabriela C. Wagner ◽  
David G. Hazlerigg ◽  
Alexander C. West
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
Activity Patterns ◽  
Bird Species ◽  
High Arctic ◽  
Photoperiodic Response ◽  
The Arctic ◽  
Pars Tuberalis ◽  
Clock Gene Expression ◽  
Adaptive Value

SUMMARYThe arctic archipelago of Svalbard (74 to 81° North) experiences extended periods of uninterrupted daylight in summer and uninterrupted darkness in winter. Species native to Svalbard display no daily rhythms in behaviour or physiology during these seasons, leading to the view that circadian rhythms may be redundant in arctic environments [1, 2]. Nevertheless, seasonal changes in the physiology and behaviour of arctic species rely on photoperiodic synchronisation to the solar year. Since this phenomenon is generally circadian-based in temperate species, we investigated if this might be a preserved aspect of arctic temporal organisation.Here, we demonstrate the involvement of the circadian clock in the seasonal photoperiodic response of the Svalbard ptarmigan (Lagopus muta hyperborea), the world’s northernmost resident bird species. First, we show the persistence of rhythmic clock gene expression under constant conditions within the mediobasal hypothalamus and pars tuberalis, the key tissues in the seasonal neuroendocrine cascade. We then employ a “sliding skeleton photoperiod” protocol, revealing that the driving force behind seasonal biology of the Svalbard ptarmigan is rhythmic sensitivity to light, a feature that depends on a functioning circadian rhythm. Our results suggest that the unusual selective pressure of the Arctic relaxes the adaptive value of the circadian clock for organisation of daily activity patterns, whilst preserving its importance for seasonal synchronisation. Thus, our data simultaneously reconnects circadian rhythms to life in the Arctic and establishes a universal principle of evolutionary value for circadian rhythms in seasonal biology.

scholarly journals Little auks under the midnight sun: diel activity rhythm of a small diving seabird during the Arctic summer

2020 ◽  
Author(s):  
Katarzyna Wojczulanis-Jakubas ◽  
Piotr Wąż ◽  
Dariusz Jakubas
Keyword(s):  
Daily Activity ◽  
Activity Rhythm ◽  
Activity Patterns ◽  
Population Level ◽  
High Arctic ◽  
The Arctic ◽  
Diel Activity ◽  
Little Auk ◽  
Individual Level ◽  
Colony Attendance

Many animal species exhibit a diel, 24-hr pattern of activity, which is steered by timing cues, with the daily light–dark cycle considered the most powerful. This cue, however, is reduced in polar zones under continuous daylight conditions associated with the midnight sun. The rhythm of animal behaviour under such conditions is poorly understood. Here, we examine periodicity and patterns of daily activity (colony attendance and foraging) in a High-Arctic seabird, the little auk (Alle alle). We demonstrated a regular rhythm of colony attendance at the population level, with birds being the most abundant in the colony during hours of relatively low sun elevation. This pattern is likely to be associated with predation pressure that may be perceived by birds as lower during hours with low sun elevation, because of better predator detectability. Regarding rhythms at an individual level, however, we found the most common periodicity to be 23.2 hr (range from 19.9 hr to 30.8 hr) but no clear pattern of daily colony attendance of individuals. Such a flexibility in daily rhythms indicates that individuals may become arrhythmic in regard to the 24-hr environmental cycle, despite regularities observed at the population level. Finally, we compared males and females in terms of daily activity patterns but we did not find significant sex differences.

scholarly journals The Clock Keeps Ticking: Circadian Rhythms of Free-Ranging Polar Bears

2020 ◽  
Vol 35 (2) ◽  
pp. 180-194 ◽  
Author(s):  
Jasmine V. Ware ◽  
Karyn D. Rode ◽  
Charles T. Robbins ◽  
Tanya Leise ◽  
Colby R. Weil ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Sea Ice ◽  
Behavioral Plasticity ◽  
Prey Availability ◽  
Activity Patterns ◽  
The Arctic ◽  
Constant Darkness ◽  
Polar Bears ◽  
Cold Temperatures ◽  
Daily Movement

Life in the Arctic presents organisms with multiple challenges, including extreme photic conditions, cold temperatures, and annual loss and daily movement of sea ice. Polar bears ( Ursus maritimus) evolved under these unique conditions, where they rely on ice to hunt their main prey, seals. However, very little is known about the dynamics of their daily and seasonal activity patterns. For many organisms, activity is synchronized (entrained) to the earth’s day/night cycle, in part via an endogenous (circadian) timekeeping mechanism. The present study used collar-mounted accelerometer and global positioning system data from 122 female polar bears in the Chukchi and Southern Beaufort Seas collected over an 8-year period to characterize activity patterns over the calendar year and to determine if circadian rhythms are expressed under the constant conditions found in the Arctic. We reveal that the majority of polar bears (80%) exhibited rhythmic activity for the duration of their recordings. Collectively within the rhythmic bear cohort, circadian rhythms were detected during periods of constant daylight (June-August; 24.40 ± 1.39 h, mean ± SD) and constant darkness (23.89 ± 1.72 h). Exclusive of denning periods (November-April), the time of peak activity remained relatively stable (acrophases: ~1200-1400 h) for most of the year, suggesting either entrainment or masking. However, activity patterns shifted during the spring feeding and seal pupping season, as evidenced by an acrophase inversion to ~2400 h in April, followed by highly variable timing of activity across bears in May. Intriguingly, despite the dynamic environmental photoperiodic conditions, unpredictable daily timing of prey availability, and high between-animal variability, the average duration of activity (alpha) remained stable (11.2 ± 2.9 h) for most of the year. Together, these results reveal a high degree of behavioral plasticity in polar bears while also retaining circadian rhythmicity. Whether this degree of plasticity will benefit polar bears faced with a loss of sea ice remains to be determined.

Suppression of men's responses to seasonal changes in day length by modern artificial lighting

1995 ◽  
Vol 269 (1) ◽  
pp. R173-R178 ◽  
Author(s):  
T. A. Wehr ◽  
H. A. Giesen ◽  
D. E. Moul ◽  
E. H. Turner ◽  
P. J. Schwartz
Keyword(s):  
Urban Environment ◽  
Rectal Temperature ◽  
Seasonal Changes ◽  
Day Length ◽  
Constant Darkness ◽  
Artificial Light ◽  
Active Secretion ◽  
Artificial Lighting ◽  
Natural Photoperiod ◽  
Low Levels

We recently reported that humans have conserved mechanisms, like those that exist in other animals, which detect changes in day length and make corresponding adjustments in the duration of nocturnal periods of secretion of melatonin and of other functions. We detected these responses in individuals who were exposed to artificial "days" of different durations. The purpose of the present study was to determine whether men who are exposed to natural and artificial light in an urban environment at 39 degrees N are still able to detect and respond to seasonal changes in duration of the natural photoperiod. We measured profiles of circadian rhythms during 24-h periods of constant darkness (< 1 lx) and found no summer-winter differences in durations of nocturnal periods of active secretion of melatonin, rising levels of cortisol, high levels of thyrotropin, and low levels of rectal temperature. The results of this and our previous study suggest that modern men's use of artificial light suppresses responses to seasonal changes in the natural photoperiod that might otherwise occur at this latitude.

scholarly journals Arctic plant diversity in the Early Eocene greenhouse

2011 ◽  
Vol 279 (1733) ◽  
pp. 1515-1521 ◽  
Author(s):  
Guy J. Harrington ◽  
Jaelyn Eberle ◽  
Ben A. Le-Page ◽  
Mary Dawson ◽  
J. Howard Hutchison
Keyword(s):  
Vegetation Type ◽  
Extreme Environments ◽  
Taxonomic Diversity ◽  
High Arctic ◽  
The Arctic ◽  
Polar Regions ◽  
Early Eocene ◽  
Diversity Gradient ◽  
The Us ◽  
Animal Communities

For the majority of the Early Caenozoic, a remarkable expanse of humid, mesothermal to temperate forests spread across Northern Polar regions that now contain specialized plant and animal communities adapted to life in extreme environments. Little is known on the taxonomic diversity of Arctic floras during greenhouse periods of the Caenozoic. We show for the first time that plant richness in the globally warm Early Eocene (approx. 55–52 Myr) in the Canadian High Arctic (76° N) is comparable with that approximately 3500 km further south at mid-latitudes in the US western interior (44–47° N). Arctic Eocene pollen floras are most comparable in richness with today's forests in the southeastern United States, some 5000 km further south of the Arctic. Nearly half of the Eocene, Arctic plant taxa are endemic and the richness of pollen floras implies significant patchiness to the vegetation type and clear regional richness of angiosperms. The reduced latitudinal diversity gradient in Early Eocene North American plant species demonstrates that extreme photoperiod in the Arctic did not limit taxonomic diversity of plants.

scholarly journals Freezer on, lights off! Environmental effects on activity rhythms of fish in the Arctic

2017 ◽  
Vol 13 (12) ◽  
pp. 20170575 ◽  
Author(s):  
Kate L. Hawley ◽  
Carolyn M. Rosten ◽  
Thrond O. Haugen ◽  
Guttorm Christensen ◽  
Martyn C. Lucas
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Individual Variability ◽  
Day Length ◽  
The Arctic ◽  
Diel Activity ◽  
Polar Regions ◽  
Winter Solstice ◽  
Activity Rhythms ◽  
Polar Day

Polar regions are characterized by acute seasonal changes in the environment, with organisms inhabiting these regions lacking diel photoperiodic information for parts of the year. We present, to our knowledge, the first high-resolution analysis of diel and seasonal activity of free-living fishes in polar waters (74°N), subject to extreme variation in photoperiod, temperature and food availability. Using biotelemetry, we tracked two sympatric ecomorphs of lake-dwelling Arctic charr ( Salvelinus alpinus n = 23) over an annual cycle. Charr activity rhythms reflected the above-surface photoperiod (including under ice), with diel rhythms of activity observed. During the dark winter solstice period, charr activity became arrhythmic and much reduced, even though estimated light levels were within those at which charr can feed. When twilight resumed, charr activity ensued as diel vertical migration, which continued throughout spring and with increasing day length, despite stable water temperatures. Diel activity rhythms ceased during the polar day, with a sharp increase in arrhythmic fish activity occurring at ice-break. Despite contrasting resource use, circannual rhythms were mirrored in the two ecomorphs, although individual variability in activity rhythms was evident. Our data support conclusions of functionally adaptive periods of arrhythmicity in polar animals, suggesting maintenance of a circannual oscillator for scheduling seasonal behavioural and developmental processes.

scholarly journals Differentiation of coarse-mode anthropogenic, marine and dust particles in the high Arctic Islands of Svalbard

2021 ◽  
Author(s):  
Congbo Song ◽  
Manuel Dall’Osto ◽  
Angelo Lupi ◽  
Mauro Mazzola ◽  
Rita Traversi ◽  
...  
Keyword(s):  
High Arctic ◽  
The Arctic ◽  
Dust Particles ◽  
Sea Spray ◽  
Polar Regions ◽  
Long Distance ◽  
Svalbard Archipelago ◽  
Coarse Mode ◽  
Arctic Haze ◽  
Natural Aerosol

Abstract. Understanding aerosol-cloud-climate interactions in the Arctic is key to predict the climate in this rapidly changing region. Whilst many studies have focused on submicron aerosol (diameter less than 1 μm), relatively little is known about the climate relevance of supermicron aerosol (diameter above 1 μm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions with diameter ranging from 0.5 to 20 μm measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols to anthropogenic (two sources, 27 %) and natural (three sources, 73 %) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 μm) aerosol. The first cluster (9 %) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18 %) to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were: open ocean sea spray aerosol (34 %), mineral dust (7 %), and an unidentified source of sea spray-related aerosol (32 %). The results suggest that sea spray-related aerosol in polar regions may be more complex than previously thought due to short/long-distance origins and mixtures with Arctic haze, biogenic and likely snow-blowing aerosols. Studying supermicron natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.

scholarly journals Congruent responses to weather variability in high arctic herbivores

2012 ◽  
Vol 8 (6) ◽  
pp. 1002-1005 ◽  
Author(s):  
Audun Stien ◽  
Rolf A. Ims ◽  
Steve D. Albon ◽  
Eva Fuglei ◽  
R. Justin Irvine ◽  
...  
Keyword(s):  
Life Histories ◽  
Rangifer Tarandus ◽  
Trophic Position ◽  
High Arctic ◽  
Climate Impact ◽  
Climate Impacts ◽  
The Arctic ◽  
Polar Regions ◽  
Arctic Ecosystems ◽  
Wildlife Populations

Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer ( Rangifer tarandus ) and sibling voles ( Microtus levis ), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem.

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