Activity rhythm in High Arctic Svalbard ptarmigan (Lagopus mutus hyperboreus)

1998 ◽  
Vol 76 (11) ◽  
pp. 2031-2039 ◽  
Author(s):  
Eirik Reierth ◽  
Karl-Arne Stokkan
Keyword(s):  
Activity Rhythm ◽  
Feeding Activity ◽  
Phase Relationship ◽  
High Arctic ◽  
Oscillator Model ◽  
The Sun ◽  
Activity Time ◽  
Intermittent Feeding ◽  
Lagopus Mutus ◽  
Activity Onset

Feeding activity was recorded in captive Svalbard ptarmigan (Lagopus mutus hyperboreus) under natural photoperiodic conditions at 70°N and 79°N. At 79°N, activity was intermittent and non-circadian in summer, when the sun was permanently above the horizon, and in midwinter, when the sun was permanently lower than 6° below the horizon. The intermittent feeding pattern was evident in summer at 70°N, whereas feeding activity in winter appeared to be entrained. In spring and autumn all birds were diurnal, with morning and evening bouts of feeding activity. The phase relationship between the onset or end of activity and the photoperiod showed marked changes, especially at 79°N, but in general, activity onset was more precise relative to twilight than activity end. At 79°N there was a sigmoidal relationship between activity time and photoperiod and activity time was longer in autumn than in spring at equal photoperiods. Based on our results, the activity pattern of Svalbard ptarmigan may be described in terms of a two-oscillator model, although a one-oscillator model cannot be excluded. The possibility is discussed that rhythmic feeding or food availability may act as a zeitgeber in addition to the light-dark cycle.

Phase-resetting action of light on the circadian activity rhythm of Rattus exulans

1983 ◽  
Vol 245 (1) ◽  
pp. R10-R17
Author(s):  
P. H. Gander ◽  
R. D. Lewis
Keyword(s):  
Activity Rhythm ◽  
Phase Relationship ◽  
Masking Effect ◽  
Phase Resetting ◽  
Response Curves ◽  
Light Pulses ◽  
Subjective Night ◽  
Activity Onset ◽  
Effect Of Light

The phase resetting action of light on the circadian rhythm of locomotor activity has been examined in wild-caught Polynesian rats (Rattus exulans). Phase-response curves to 4-, 8-, and 16-h light pulses have been derived. All three curves conform to the generalization that pulses occurring during late subjective day and early subjective night produce delays, whereas advances occur in response to pulses coinciding with the late subjective night and early subjective day. Weak (type 1) phase resetting is observed in response to 4-h pulses and perhaps 8-h pulses, whereas strong (type 0) resetting apparently occurs in response to 16-h pulses. These data evidently constitute the first report of strong phase resetting in mammalian circadian rhythms. The phase relationship between an entrained activity rhythm and the light-dark cycle is dependent on the photoperiod and, in 24-h cycles, on the period difference between the rhythm and the zeitgeber. In longer zeitgeber cycles, activity onset is delayed by a direct masking effect of light. A primarily nonparametric action of light in natural entrainment is consistent with these data and with field observations.

Activity rhythm in High Arctic Svalbard ptarmigan (Lagopus mutus hyperboreus)

1998 ◽  
Vol 76 (11) ◽  
pp. 2031-2039 ◽  
Author(s):  
Eirik Reierth ◽  
Karl-Arne Stokkan
Keyword(s):  
Activity Rhythm ◽  
High Arctic ◽  
Lagopus Mutus

Simulating the action of zeitgebers on a coupled two-oscillator model of the human circadian system

1984 ◽  
Vol 247 (3) ◽  
pp. R418-R426
Author(s):  
P. H. Gander ◽  
R. E. Kronauer ◽  
C. A. Czeisler ◽  
M. C. Moore-Ede
Keyword(s):  
Core Temperature ◽  
Activity Rhythm ◽  
Human Subjects ◽  
Model Performance ◽  
The Other ◽  
Oscillator Model ◽  
Temporal Isolation ◽  
The Core ◽  
Temperature Rhythm ◽  
Rest Activity

Our two-oscillator model was originally designed to describe the circadian rhythms of human subjects maintained in temporal isolation. The performance of this model in response to simulated environmental synchronizing cycles (zeitgebers) is examined here. Six distinct types of synchronization are demonstrated between the x oscillator (postulated to regulate the core temperature rhythm), the y oscillator (postulated to regulate the rest-activity rhythm), and z (the zeitgeber). Four types of synchronization are identifiable, if we consider only the periods of the three oscillators. Both x and y may be synchronized by z; either may synchronize with z while the other exhibits a different period; or x, y, and z may each show different periods. Two further classes of synchronization are discernible when phase criteria are taken into account. When either x or y is on the verge of desynchronizing from the other two oscillators, it undergoes periodic phase modulations while retaining the common overall period. The type of synchronization observed depends on the periods of x, y, and z and on the strength of the z drive. The effects of modifying each of these parameters have been systematically investigated by simulation, and model performance is summarized in terms of range of entrainment "maps." These constitute extensive sets of predictions about expected patterns of entrainment of the core temperature and rest-activity rhythms of human subjects exposed to various environmental zeitgebers. Experimental data are available against which model predictions can be tested.

Photoperiod alters phase difference between activity onset in vivo and mPer2::luc peak in vitro

2008 ◽  
Vol 295 (5) ◽  
pp. R1688-R1694 ◽  
Author(s):  
Carl T. Mickman ◽  
Jeremy S. Stubblefield ◽  
Mary E. Harrington ◽  
Dwight E. Nelson
Keyword(s):  
Phase Relationship ◽  
Stable Phase ◽  
Light Cycle ◽  
Behavioral Rhythms ◽  
Activity Onset ◽  
Long Photoperiod ◽  
Initial Cycle ◽  
Phase Relationships

Photoperiod is a significant modulator of behavior and physiology for many organisms. In rodents changes in photoperiod are associated with changes in circadian period and photic resetting of circadian pacemakers. Utilizing rhythms of in vivo behavior and in vitro mPer2::luc expression, we investigated whether different entrainment photoperiods [light:dark (L:D) 16:8 and L:D 8:16] alter the period or phase relationships between these rhythms and the entraining light cycle in Per2::luc C57BL/6J mice. We also tested whether mPer2::luc rhythms differs in anterior and posterior suprachiasmatic nucleus (SCN) slices. Our results demonstrate that photoperiod significantly changes the timing of the mPer2::luc peak relative to the time of light offset and the activity onset in vivo. In both L:D 8:16 and L:D 16:8 the mPer2::luc peak maintained a more stable phase relationship to activity offset, while altering the phase relationship to activity onset. After the initial cycle in culture, the period, phase, and peaks per cycle were not significantly different for anterior vs. posterior SCN slices taken from animals within one photoperiod. After short-photoperiod treatment, anterior SCN slices showed increased-amplitude Per2::luc waveforms and posterior SCN slices showed shorter-duration peak width. Finally, the SCN tissue in vitro did not demonstrate differences in period attributable to photoperiod pretreatment, indicating that period aftereffects observed in behavioral rhythms after long- and short-day photoperiods are not sustained in Per2::luc rhythms in vitro. The change in phase relationship to activity onset suggests that Per2::luc rhythms in the SCN may track activity offset rather than activity onset. The reduced amplitude rhythms following long-photoperiod treatment may represent a loss of coupling of component oscillators.

Response of hamster circadian system to transitions between light and darkness

1986 ◽  
Vol 250 (4) ◽  
pp. R708-R711 ◽  
Author(s):  
H. E. Albers
Keyword(s):  
Activity Rhythm ◽  
Phase Shifts ◽  
Circadian System ◽  
Circadian Cycle ◽  
Circadian Activity ◽  
Syrian Hamsters ◽  
Circadian Activity Rhythm ◽  
Free Running ◽  
Activity Onset

The effects of exposure to sudden transitions from dark to light (DL) and light to dark (LD) were determined on the free-running circadian activity rhythm of Syrian hamsters. The activity rhythm was phase delayed by 1-2 h by DL transitions provided during the 12-h interval before activity onset (subjective day). In contrast, DL transitions produced phase advances of approximately 1 h 2-12 h after activity onset. LD transitions tended to produce phase advances throughout the circadian cycle. During the subjective day, LD transitions resulted in phase advances of up to 4 h. After the onset of activity, LD transitions produced phase advances of a lesser magnitude than during the subjective day. In addition, some phase delays were also observed. When the phase shifts produced by DL and LD transitions were combined additively these transitions could account for the phase shifts previously reported for brief pulses of light.

Interactions Between Introduced and Native Millipede Species in South Australia

1995 ◽  
Vol 43 (2) ◽  
pp. 129 ◽  
Author(s):  
TT Griffin ◽  
CM Bull
Keyword(s):  
Introduced Species ◽  
Native Species ◽  
Feeding Activity ◽  
South Australia ◽  
Habitat Choice ◽  
Activity Time ◽  
Species Overlap ◽  
Ecological Changes ◽  
Significant Difference ◽  
Very High

The Portugese millipede Ommaroiulus moreleti (Lucas) (Diplopoda:Julidae) has recently been introduced to South Australia where it has reached very high densities. In parts of the Adelaide Hills it now co-occurs with two native millipedes, Oncocladosoma clavigerum Jeekel (Diplopoda: Paradoxosomatidae) and Dimerogonus orophilus (Attems) (Diplopoda: Cambalidae). We attempted to show whether the introduced species, which has successfully invaded the detrivore community, has affected the ecology or behaviour of the native millipede members of that community. Experiments in laboratory and field arenas showed that the three species overlap broadly in activity time and microhabitat. The two native species showed no significant difference in habitat choice or aggregating behaviour when alone or mixed with the introduced O. moreleti, and the natives commonly aggregated with the introduced species. Although D. orophilus had reduced feeding activity in the presence of O. moreleti, neither native species rejected food that had been in contact with O. moreleti. We conclude that direct interactions between the introduced invader and the native species cause few behavioural or ecological changes within the detrivorous millipede community.

scholarly journals On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers

2011 ◽  
Vol 366 (1565) ◽  
pp. 772-782 ◽  
Author(s):  
Gábor Horváth ◽  
András Barta ◽  
István Pomozi ◽  
Bence Suhai ◽  
Ramón Hegedüs ◽  
...  
Keyword(s):  
North Atlantic ◽  
Laboratory Experiments ◽  
High Arctic ◽  
Exact Nature ◽  
The Sun ◽  
Birefringent Crystal ◽  
The North ◽  
Open Sea ◽  
Skylight Polarization ◽  
The North Atlantic

Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as ‘sunstone’ in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic.

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.

Behavioural Thermoregulation in the Freeze-Tolerant Arctic Caterpillar, Gynaephora Groenlandica

1988 ◽  
Vol 138 (1) ◽  
pp. 181-193 ◽  
Author(s):  
OLGA KUKAL ◽  
BERND HEINRICH ◽  
JOHN G. DUMAN
Keyword(s):  
Solar Radiation ◽  
Growth And Development ◽  
High Arctic ◽  
The Sun ◽  
Metabolic Rates ◽  
Behavioural Thermoregulation ◽  
Body Temperatures ◽  
Feeding Site ◽  
Freeze Tolerant ◽  
Gynaephora Groenlandica

Larvae of the high arctic caterpillar, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae) spent most (60 %) of their time orienting towards the sun (i.e. basking) and only 20% feeding, primarily near midday. Larvae usually basked after feeding, then either fed again or moved to a new feeding site. Basking larvae reached their highest body temperatures (Tb) of ≊30°C (≊20°C in excess of the ambient temperature) when surrounded by snow on a calm day in the midday sun. Setae significantly decreased larval cooling rates. Maximal metabolic rates were attained in basking larvae, but at body temperatures below 10°C oxygen uptake was greatly reduced. Our studies indicate that G. groenlandica larvae are behaviourally adapted to utilize available solar radiation for growth and development.

Hypobaric Hypoxia: Within-Subject Transition Effects in Albino Rats

1972 ◽  
Vol 35 (3) ◽  
pp. 799-806
Author(s):  
Ray T. Sterner ◽  
Gary D. Schwank
Keyword(s):  
Spontaneous Activity ◽  
Hypobaric Hypoxia ◽  
Feeding Activity ◽  
Exposure Period ◽  
Albino Rats ◽  
Light Cycle ◽  
Activity Time ◽  
Subject Design ◽  
Transition Effects ◽  
Period Return

The effect of rapid hypobaric transition (1 hr.) upon water consumption, food consumption, body weight, feeding activity and spontaneous activity of albino rats was studied using a within-subject design. Transition from 635 ± 5 mm. Hg. (5,000 ft.) to 455 ± 5 mm. Hg. (14,000 ft.) induced temporary hypophagia, hypodipsia and concomitant weight loss; gradual recovery occurred during the exposure period; return to 635 ± 5 mm. Hg. after 7 days abruptly (≤ 24 hr.) alleviated these effects. Alterations in feeding activity (time-in-foodwell) during the off portions of the light cycle paralleled food intake changes. No reliable changes in spontaneous activity as a function of hypobaric transition were noted. Results were interpreted as suggestive of hypothalamic and frontal cortex involvement in hypoxia-induced behavioral shifts.

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