Social cues can play a role in timing onset of the breeding season of the ewe

Wayne, Nancy L.; Malpaux, Benoît; Karsch, Fred J.

doi:10.1530/jrf.0.0870707

Cited by 36 publications

(20 citation statements)

References 25 publications

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“…In talapoin monkeys, differences in the timing of the breeding season can be observed in animals sharing the same environment but residing in different social groups [Rowell & Dixson, 1975]. Pinealectomized ewes exhibit a delay in annual surges in luteinizing hormone (LH) when socially isolated but exhibit a normal rhythm if kept in a flock of intact ewes [Wayne et al, 1989]. In this case, social partners facilitate the synchronization of LH secretion in individuals incapable of responding to photoperiodic input.…”

Section: Discussionmentioning

confidence: 99%

Annual physiological changes in individually housed squirrel monkeys (Saimiri sciureus)

et al. 1999

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This study investigated whether annual changes in physiology occur in individually housed squirrel monkeys (Saimiri sciureus). Physiological measures were monitored for 20 months. Over the course of the study, all individually housed males and females exhibited clear annual changes in gonadal and adrenal hormone levels, and males exhibited species‐typical changes in body weight. Females exhibited a typical pattern of hormonal changes, with elevations in gonadal steroids occurring during the same months as elevations in cortisol. Males, however, exhibited an atypical pattern, as elevations in hormone levels were not synchronized with each other; rather, elevations in testosterone occurred out of phase with changes in cortisol and body weight. The timing of annual events in individually housed subjects was compared to that in nearby social groups, in which the timing of the breeding season from year to year was determined by social group formations and was outside the naturally occurring breeding season. Elevations of ovarian and adrenocortical hormones in individually housed females were synchronized with indices of breeding in heterosexual social groups. Similarly, weight gain in males was associated with elevations in cortisol and, as with socially housed males, tended to precede seasonal breeding in the social groups. In contrast, annual testosterone elevations for individually housed males were not synchronized with breeding in nearby social groups. We conclude that direct physical interaction is not required for the annual expression of breeding readiness. Synchrony of seasonality among squirrel monkeys may be accomplished by distant social cues in females, but males may require physical interaction for complete synchrony of annual physiological changes. Am. J. Primatol. 47:93–103, 1999. © 1999 Wiley‐Liss, Inc.

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Section: Discussionmentioning

confidence: 99%

Annual physiological changes in individually housed squirrel monkeys (Saimiri sciureus)

et al. 1999

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“…All ewes were maintained with rams and other ewes prior to pinealectomy; thereafter they were physically isolated in a pasture separate from rams and other ewes to minimize social influences on reproductive function. (Spring pinealectomized ewes served as a control in another study; Pinx Isolated group in Wayne et al 1989). The control group consisted of pinealintact ewes for determination of the normal seasonal reproductive cycle in each of the two years of the study.…”

Section: Methodsmentioning

confidence: 99%

Photoperiodic requirements for timing onset and duration of the breeding season of the ewe: Synchronization of an endogenous rhythm of reproduction

1990

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A study was conducted to test the hypothesis that different portions of the annual photoperiodic cycle play different roles in timing the breeding season of the ewe, Ovis aries, an animal in which an endogenous rhythm generates the seasonal reproductive transitions. Adult female sheep were pinealectomized to disrupt transduction of photoperiodic cues at 4 times of the year (summer and winter solstices, vernal and autumnal equinoxes), and the effects on seasonal reproductive neuroendocrine activity were evaluated. Time of pinealectomy greatly influenced the subsequent seasonal reproductive cycle such that the following inferences are possible. Lengthening days between the winter and summer solstices synchronize reproductive onset to the appropriate time of year. The relatively long days around the summer solstice act to suppress reproductive activity and forestall the start of the breeding season until late summer/early autumn. The shortening days between the summer solstice and autumnal equinox maintain a normal intensity and duration of reproductive neuroendocrine induction during the impending breeding season. However, the shortening days between the autumnal equinox and winter solstice (i.e., after breeding season onset) do not appear to play a critical role in maintaining the breeding season of that year, but may provide important cues for timing the breeding season of the following year.

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“…Although ecological factors are undoubtedly important in timing seasonal transitions, there is considerable evidence in squirrel monkeys and other seasonally breeding animals that the coordination of reproductive changes between individuals is mediated by social stimulation [38,39]. In squirrel monkeys, formation of new social groups at most times of the year can increase gonadal activity to levels indicative of breeding readiness in both males and females [21,26,27] and group formation can alter the timing of subsequent breeding seasons [10,29].…”

mentioning

confidence: 99%

Seasonality in squirrel monkeys (Saimiri sciureus): Social facilitation by females

Schiml¹,

Mendoza²,

Saltzman³

et al. 1996

Physiology & Behavior

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Social cues can play a role in timing onset of the breeding season of the ewe

Cited by 36 publications

References 25 publications

Annual physiological changes in individually housed squirrel monkeys (Saimiri sciureus)

Annual physiological changes in individually housed squirrel monkeys (Saimiri sciureus)

Photoperiodic requirements for timing onset and duration of the breeding season of the ewe: Synchronization of an endogenous rhythm of reproduction

Seasonality in squirrel monkeys (Saimiri sciureus): Social facilitation by females

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