Internalization of seasonal time

  title={Internalization of seasonal time},
  author={Brian J. Prendergast},
  journal={Hormones and Behavior},
Avian circannual systems: persistence and sex differences.
  • S. RaniVinod Kumar
  • Biology, Environmental Science
    General and comparative endocrinology
  • 2013
Hormones and Reproductive Cycles in Rodents
Photoperiodic time measurement and seasonal immunological plasticity
Climate change and seasonal reproduction in mammals
  • F. Bronson
  • Environmental Science
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2009
The neuroendocrine pathways via which foraging conditions and predictive cues such as photoperiod enforce seasonality are discussed, and the kinds of seasonal challenges mammals actually face in natural habitats are considered.
Information theory and the neuropeptidergic regulation of seasonal reproduction in mammals and birds
The constancy/contingency model of predictability is applied to investigate how GnRH1 and Kiss1 integrate different environmental cues to regulate reproduction and shows that variation in Gn RH1 from a highly seasonal avian species exhibits a predictive change that is primarily based on contingency information.
Environmental cues trigger seasonal regression of primary and accessory sex organs of the mud snail, Ilyanassa obsoleta
Whether the seasonal onset of regression in mud snails is controlled by two environmental cues, photoperiod or temperature is investigated, which is an accurate predictor of changing seasons.
The interplay between seasonality and density: consequences for female breeding decisions in a small cyclic herbivore
During the main breeding season, variability of female vole reproduction is predominantly shaped by food resources, suggesting that only highly productive environment may induce vole outbreaks, and that negative direct density dependence on reproduction could explain winter declines after outbreaks.
Microevolution of neuroendocrine mechanisms regulating reproductive timing in Peromyscus leucopus.
The apparent multiple sources of genetic variation within this population suggest that there may be multiple alternative combinations of alleles for both the R and NR phenotypes, and supports the hypothesis that genetic variation in characteristics of GnRH neurons themselves may be responsible for the observed phenotypic variation in reproduction in SD.
A review of seasonal/circannual effects of laboratory rodent behavior


Establishment and persistence of photoperiodic memory in hamsters.
Findings indicate that hamsters are influenced only by relatively recent day lengths and melatonin signals and ignore earlier ones that might cause them to misinterpret the salience of current day lengths.
Genetic Analyses of a Seasonal Interval Timer
Balancing selection in environments where the onset of spring conditions varies from year to year could maintain genetic variance in interval timers and yield interval timers tuned to the local environment.
Seasonal adaptations of Siberian hamsters. II. Pattern of change in daylength controls annual testicular and body weight rhythms.
Seasonal fluctuations in testis size and body weight in Siberian hamsters maintained in a year-long pattern of increasing and decreasing DLs are determined to show the photoperiodic history determines gonadal responses over a broad range ofDLs and influences gonadal responsiveness to short DLs and the triggering of the interval timer underlying recrudescence.
Mammalian Photoperiodic System: Formal Properties and Neuroendocrine Mechanisms of Photoperiodic Time Measurement
  • B. Goldman
  • Biology
    Journal of biological rhythms
  • 2001
Variations in photoperiodic response are seen not only between species but also between breeding populations within a species and between individuals within single breeding populations, and among species differences with respect to the importance and specific functions of various melatonin target sites.
Melatonin Implants Disrupt Developmental Synchrony Regulated By Flexible Interval Timers
  • M. Gorman
  • Biology
    Journal of neuroendocrinology
  • 2003
The results demonstrate that the function of the interval timer underlying photorefractoriness is influenced by photoperiod and by melatonin, and the endogenous pattern of melatonin signals adjusts the duration measured by the intervals to insure that developmental milestones of seasonal cohorts are synchronized with environmental conditions.
Conservation of photoperiod-responsive mechanisms in humans.
Differences persisted during 24-h periods of enforced wakefulness in constant dim light, indicating that prior exposure to the two regimes induced abiding changes in the timing of internal processes, such as circadian pacemaker oscillations, that control the durations of nocturnal and diurnal periods of the rhythms.
Temporal changes in gene expression in the arcuate nucleus precede seasonal responses in adiposity and reproduction.
Genes described here are related to photoperiodic programming of the neuroendocrine hypothalamus through expression responses within a subdivision of the arcuate nucleus in photorefractory hamsters.
Clock genes in calendar cells as the basis of annual timekeeping in mammals--a unifying hypothesis.
The current challenge is to identify other calendar cells in the central nervous system regulating long-term cycles in reproduction, body weight and other seasonal characteristics and to establish whether clock genes provide a conserved molecular mechanism for long- term timekeeping.
Seasonal adaptations of Siberian hamsters. I. Accelerated gonadal and somatic development in increasing versus static long day lengths.
Gradual increases in DL resulted in more rapid somatic development than did gestation and maintenance in a static 12L photoperiod, and the pattern of gradual increases was not sufficient to accelerate development at all DLs but was effective in the range of 12L to 19L.