Where clocks are redundant: weak circadian mechanisms in reindeer living under polar photic conditions

Oort, Bob van; Tyler, N. J. C.; Gerkema, Menno P.; Folkow, Lars P.; Stokkan, Karl‐Arne

doi:10.1007/s00114-006-0174-2

Cited by 93 publications

(92 citation statements)

References 41 publications

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“…Erriksson et al, 1981;Tokura and Aschoff, 1983;Hastings et al, 1998;Pohl, 1998;Mistlberger and Skene, 2004;van Oort et al, 2007;Mircsof and Brown, 2013;El Allali et al, 2013;LeGates et al, 2014). The presence of several secondary zeitgebers (such as ambient temperature, patterns of eating and drinking, social influences and physical activity) that allow the entrainment of circadian rhythms in the absence of light is also well accepted (e.g.…”

Section: Temperature As a Dominant Modifier Of Activity Rhythms In Thmentioning

confidence: 99%

“…Daan and Aschoff, 1975;LeGates et al, 2014), but several secondary zeitgebers or modifiers of light entrained patterns (such as temperature, patterns of eating and drinking, social influences and physical activity) allow the entrainment of circadian rhythms in the absence of, or in concert with, the primary light zeitgeber (e.g. Erriksson et al, 1981;Tokura and Aschoff, 1983;Hastings et al, 1998;Pohl, 1998;Mistlberger and Skene, 2004;van Oort et al, 2007;Mircsof and Brown, 2013;El Allali et al, 2013). Intricately linked with the circadian entrained daily activity pattern is the timing of sleep, as sleep mostly occurs in the daily phase of general and prolonged inactivity (Monk, 1991).…”

Section: Introductionmentioning

confidence: 99%

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Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns

et al. 2016

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The Arabian oryx inhabits an environment where summer ambient temperatures can exceed 40°C for extended periods of time. While the oryx employs a suite of adaptations that aid survival, the effects of this extreme environment on inactivity/sleep, where ambient temperatures often exceed mammalian thermoneutral zones, are unknown.To determine how the oryx manages inactivity/sleep seasonally we used fine and coarsegrain actigraphy, in 16 animals, to reveal when the animals were inactive/sleeping in relation to variations in ambient temperatures and light levels. We demonstrate that during the cooler winter months the oryx is inactive/sleeping during the cooler parts of day (pre-dawn hours), showing a diurnal activity pattern. In contrast, in the summer months, the oryx displayed a crepuscular activity pattern, with the major inactivity/sleep bouts occurring equally during both the coolest part of the night (pre-dawn hours) and the hottest part of the day (afternoon hours). Interestingly, the daily rhythm of the timing of changes in core body temperature did not vary seasonally, although the amplitude did change. The transition from winter diurnal activity to summer crepuscular activity occurred in May, while the reverse occurred in September. By having half of the major summer sleep bouts during the hottest part of the day, the oryx may take advantage of the thermoregulatory physiology of sleep to mitigate increases in body temperature. The seasonal summer desynchronization of circadian entrained daily rhythms (core body temperature and daily activity patterns) is suggestive of temperature acting to mask, or modify, output pathways from the suprachiasmatic nucleus.

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Section: Temperature As a Dominant Modifier Of Activity Rhythms In Thmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns

et al. 2016

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“…It has been demonstrated that reindeer (Rangifer tarandus) show daily modulation of behaviour only in spring and in autumn. During continuous darkness in winter and continuous light in summer, they show no 24 h modulation of their rest-activity pattern [51,52] or plasma melatonin levels [53,54]. Apparently, the lack of 24 h rhythmicity in the environment at some parts of the year leads this species to a complete or partial loss of the circadian system at the molecular level [54].…”

Section: Adjustment To Changing Day Length As a Selection Force For Tmentioning

confidence: 99%

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Hut

Beersma

2011

Phil. Trans. R. Soc. B

183

193

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Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.

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“…Polar species show a range of behavioural patterns in the absence of the predominant light-dark cycle, including arrhythmicity, free-running rhythms, and entrained rhythms [4,5]. The nature of selection on biological rhythms may dictate whether rhythms persist during polar night or polar day [4], such that reindeer (Rangifer tarandus) may become arrhythmic to maximize foraging opportunity [6], whereas semipalmated sandpipers (Calidris pusilla) providing biparental care may maintain socially synchronized rhythms that may increase breeding success and foraging opportunities [5,7].…”

Section: Introductionmentioning

confidence: 99%

Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird

Huffeldt

Merkel

2016

Biol. Lett.

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In contrast to daily rhythms that are common in the presence of the geophysical light-dark cycle, organisms at polar latitudes exhibit many diel activity patterns during natural periods of continuous solar light or darkness (polar day and night, respectively), from 24 h rhythms to arrhythmicity. In Arctic Greenland (73.78 N, 56.68 W) during polar day, we observed breeding-site attendance rhythms of thick-billed murres (Uria lomvia; n ¼ 21 pairs), a charadriiform seabird, which provide biparental care at the colony. We found that U. lomvia egg-incubation and chick-brooding attendance is rhythmic and synchronized to the geophysical day (mean period length [rhythm duration] + 95% confidence interval ¼ 24.13 + 0.52 h). Individual pair members had temporally segregated, sex-specific colony-attendance rhythms that were opposite (inverted) to each other, and these sex-specific rhythms were prominent at the population level. Our results provide a basis for investigating circadian systems at polar latitudes and sex-specific parental-care strategies.

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Where clocks are redundant: weak circadian mechanisms in reindeer living under polar photic conditions

Cited by 93 publications

References 41 publications

Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns

Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird

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