The effect of light on the free running circannual rhythm of the golden-mantled ground squirrel, Citellus lateralis

Pengelley, Eric T.; Asmundson, Sally J.

doi:10.1016/0010-406x(70)90930-8

Cited by 33 publications

(10 citation statements)

References 11 publications

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“…Unfortunately, due to the 4-to 5-year lifespan of rainbow trout broodstock, it was not possible to continue the experiment for several more cycles to establish whether the rhythm showed a steady-state periodicity, or, as observed, was inherently at UNIVERSITY OF TOLEDO LIBRARIES on March 16, 2015 jbr.sagepub.com Downloaded from 52 variable. Similar to previous studies, it is possible that the observed periodicities of the spawning rhythms were examples of transient cycles, not characteristic of the periodicity of the rhythm in steady state (Pengelley and Asmundson, 1970;Ducker et al, 1973;Berthold, 1978). If we accept the possibility that the results may be manifestations of transient cycles, these results indicate that if the circannual rhythm of gonadal maturation is driven by some form of internal timing mechanism or &dquo;clock,&dquo; then it is rather inaccurate and irregular in its oscillation.…”

supporting

confidence: 60%

Circannual Rhythms of Gonadal Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Duston

Bromage

1991

J Biol Rhythms

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Individually identified, 2-year-old female rainbow trout were maintained for up to 51 months on a constant schedule of 6 hr light and 18 hr darkness (LD 6:18), constant temperature (8.5-9.0 degrees C), and constant feeding rate. The fish exhibited free-running circannual rhythms of gonadal maturation and ovulation, which were self-sustaining for up to three cycles. The periodicity of the rhythm showed variation between fish and in successive cycles for the same fish, ranging from approximately 11 to 15 months.

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supporting

confidence: 60%

Circannual Rhythms of Gonadal Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Duston

Bromage

1991

J Biol Rhythms

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“…12 The average body mass period (τ bm ) of animals exposed to high temperature was about 0.942 years, which was slightly longer than the period recorded in animals exposed to cold (0.906 years; TABLE 1). 9 Experiments with the same ground squirrel maintained for four consecutive years at 3°C, showed that body mass rhythm was phase-locked with H-A rhythm, 13 which was confirmed in other hibernators. However, it is possible to dissociate these rhythms.…”

Section: Body Mass and Hibernation-activity Cycles In Free-running Comentioning

confidence: 75%

Some Components of Hibernation Rhythms

Živadinović

Marjanović

Andjus

2005

Annals of the New York Academy of Sciences

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At low ambient temperatures some small mammals drastically reduce their body temperature and enter a state of dormancy known as hibernation. They exhibit endogenous rhythms of heterothermy/homeothermy and body mass fluctuations with the period close to one year. At high ambient temperature only body mass cycling is expressed for almost one year as well. The effect of temperature on circannual periods of some biological rhythms in different hibernators in free-running conditions as well as the circaseptal character of the intrahibernation rhythm of periodic arousals are reviewed.

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“…Rams exhibit a robust circannual rhythm of prolactin secretion under long photoperiods, but rhythmicity is weak or absent in short photoperiods (Howles et al 1982;Langford et al 1987;Lincoln & Clarke 2000). In contrast, obligate circannual species such as the golden-mantled ground squirrel display circannual cycles under all photoperiodic conditions tested, including constant light and constant darkness (Pengelley & Asmundson 1970;Zucker & Boshes 1982;Zucker et al 1983). Permissive photoperiods may reveal the sequential activation of interval timers that is otherwise suppressed.…”

Section: A Possible Synthesis: Are Circannual Clocks Constructed Frommentioning

confidence: 99%

Tracking the seasons: the internal calendars of vertebrates

Paul

Zucker

Schwartz

2007

Phil. Trans. R. Soc. B

173

152

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Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.Keywords: seasonality; photoperiodism; circannual; interval timers While the Earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease.Genesis 8: 22, King James Version (1611) As the Earth makes its yearly orbit around the Sun, the planet's 23.58 axial tilt leads to the cyclical environmental changes that we call the seasons. Recurrent challenges to the survival of organisms and their offspring arise with the dawning of each new season, and animals have evolved seasonally induced changes in phenotype that adapt them to these predictable events. For example, in many temperate environments, winter is generally characterized by severe decreases in ambient temperature and food availability, leading to increased energetic demands at a time when resources are diminished. Because energy requirements of female mammals typically increase markedly during lactation (Bronson 1989) and newly weaned offspring are particularly vulnerable to environmental perturbations (Hill 1992), raising offspring during this time of year is often futile. Thus, many temperate species have evolved winter-specific behaviours and physiology to conserve energy (e.g. hibernation, a more insulative pelage, huddling) or provide for escape (e.g. migration). Many species also increase the chances of offspring survival by timing their mating behaviours so that parturition occurs during energetically favourable times of year.

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The effect of light on the free running circannual rhythm of the golden-mantled ground squirrel, Citellus lateralis

Cited by 33 publications

References 11 publications

Circannual Rhythms of Gonadal Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Circannual Rhythms of Gonadal Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Some Components of Hibernation Rhythms

Tracking the seasons: the internal calendars of vertebrates

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