Chemical and Behavioral Stimulation from Females Accelerates Recrudescence in Male Syrian Hamsters Exposed to Short Days

Honrado, Gerry I.; Fleming, Alison S.

doi:10.1177/074873049601100203

Cited by 7 publications

(1 citation statement)

References 22 publications

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“…Evidently some nonphotoperiodic seasonal factor(s) must override the normal photoperiodic input in the wild. Food, water, ambient temperature and social cues have all been shown to alter seasonal traits ( Whitsett & Lawton 1982;Desjardins & Lopez 1983;Eskes 1983;Nelson et al 1983;Pearce & Oldham 1988;Schneider & Wade 1989;Wayne et al 1989;Honrado & Fleming 1996;Hegstrom & Breedlove 1999;Kriegsfeld et al 2000a,b;Larkin et al 2001Larkin et al , 2002Reynolds et al 2003;Schoech et al 2004;Genin et al 2005), including a single plant compound identified in newly grown vegetation that stimulates reproduction in wild montane voles (Microtus montanus) during the winter months (Berger et al 1981).…”

Section: (C) Timers Versus Clocksmentioning

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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