Synchronization of circannual cycles: a cold spring delays the cycles of thirteen-lined ground squirrels

Joy, Janet E.; Mrosovsky, N.

doi:10.1007/bf00610673

Cited by 15 publications

(12 citation statements)

References 36 publications

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“…Circannual rhythms of molting occur in squirrels and minks (Davis andSwade 1983, Martinet et al 1992). In these animals, the summer and winter pelts mainly differ in pelage type and density (Rust et al 1965, Walsberg et al 1997, and the photoperiod regimen seems to be the zeitgeber for minks (Martinet et al 1992) while temperature, rather than photoperiod, the zeitgeber for squirrels (Joy and Mrosovsky 1985).…”

Section: Discussionmentioning

confidence: 99%

“…Castrucci E-mail: amdlcast@ib.usp.br (Duncan et al 1985, Rust and Meyer 1969, Smale et al 1988). Minks and squirrels present an endogenous rhythm of molt which is strongly influenced by changes in photoperiod (Martinet et al 1992) or temperature (Joy and Mrosovsky 1985). Both species also possess endogenous annual rhythms in body weight (Martinet et al 1992, Pengelley andAsmundson 1969) as do European hamsters (Masson-Pevet et al 1994) and dormice (Mrosovsky 1977).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal pelage color change: news based on a South American Rodent

Camargo

Colares

Castrucci

2006

An. Acad. Bras. Ciênc.

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Mammalian seasonalmolting and color change are known to be influenced by photoperiod changes. Calomys laucha, a South American rodent, exhibits seasonal pelage color change; however, unlike Northern hemisphere rodents, which present a gray or brown color during summer and a whitish color during winter, C. laucha pelage changes from an orange color during summer to a dark gray color during winter. Animals maintained for over a year in stationary photoperiod (LD 12:12h, 22 • C) presented orange pelage color during the summer corresponding month (January), and gray color during the winter corresponding month (July). Same age animals were evaluated during summer or winter months, and also showed different colors. Animals exposed for 12 weeks to summer or winter artificial conditions displayed color change, not according to the environmental conditions, as expected, but similar to that of animals maintained in stationary photoperiod. These results suggest that pelage color change in C. laucha is controlled by an endogenous circannual rhythm. The adaptive function of C. laucha color change is discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seasonal pelage color change: news based on a South American Rodent

Camargo

Colares

Castrucci

2006

An. Acad. Bras. Ciênc.

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“…The di!erence between a rhythmic event generated by a cycle like this and a rhythm that results from a limit cycle is stressed in Rossetti et al (1989). In a cycle comprising a sequence of stages, separate events play a functional role in generating the periodicity, each one taking an amount of time to complete and then leading to the next (Mrosovsky, 1970;Joy & Mrosovsky, 1985).…”

Section: Cycles Comprising Sequences Of Stagesmentioning

confidence: 98%

Coupled Biological Oscillators in a Cave Insect

Oda

Caldas

Piqueira

et al. 2000

Journal of Theoretical Biology

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“…It is less common at 11 ~ than at 4~ Therefore, it was suggested that thresholds vary: for some individuals slight warmth in the spring may be enough for the rhythm to progress. In such animals only very cold subzero conditions would arrest the rhythm (Mrosovsky and Lang 1971;Joy and Mrosovsky 1985;Mrosovsky 1986).…”

Section: Discussionmentioning

confidence: 99%

“…Temperature effects do not exclude the possibility that photoperiod may also have some synchronizing role for ground squirrels. However, the evidence for photoperiodic effects is quite weak (Davis and Swade 1983 ; see also Gwinner 1986), while prolonged low temperature can produce phase delays of up to 4 months (Mrosovsky 1980a) or even an arrest of the rhythm in the spring phase of low body weight, pigmented scrotum and descended testes (Mrosovsky and Lang 1971;Joy and Mrosovsky 1985). Therefore, it is worth investigating temperature as a cue that might synchronize free-running circannual rhythms to the solar year.…”

Section: Introductionmentioning

confidence: 99%

Circannual cycles in golden-mantled ground squirrels: fall and spring cold pulses

Mrosovsky

1990

J Comp Physiol A

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Endogenous circannual rhythms of male golden-mantled ground squirrels (Spermophilus lateralis) exposed to low ambient temperature (6 ~ at various times were compared to the rhythms of a control group kept in a warm room (21 ~ throughout. A 20-week pulse of cold in the spring delayed the subsequent peak body weight and molt offset. However, in the second year after the spring cold pulse, a delay in the rhythm was evident only using peak weight as a phase marker. A 20-week cold pulse in the fall resulted in an earlier peak body weight and earlier onset of pigmented scrotum and descended testes, but there was no evidence from subsequent years that rhythms had been phase advanced. A third of the animals kept continuously at 6 ~ remained with pigmented scrotum, descended testes and low body weight for more than a year. Circannual periodicities of animals that continued to display rhythms in the cold room were not significantly longer than those of controls in the warm room. The results suggest that low temperature in the fall can alter the expression of circannual rhythms without much affecting their phasing, while low temperature in the spring produces phase delays which last longer but have not been proved to be persistent.

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Synchronization of circannual cycles: a cold spring delays the cycles of thirteen-lined ground squirrels

Cited by 15 publications

References 36 publications

Seasonal pelage color change: news based on a South American Rodent

Seasonal pelage color change: news based on a South American Rodent

Coupled Biological Oscillators in a Cave Insect

Circannual cycles in golden-mantled ground squirrels: fall and spring cold pulses

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