Daylength and Control of Seasonal Reproduction in Male Birds

Wilson, Fred E.; Donham, Richard S.

doi:10.1007/978-1-4612-3740-2_6

Cited by 34 publications

(28 citation statements)

References 71 publications

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“…If an individual is able to measure the current photoperiod and ascertain whether the photoperiod is decreasing or increasing, it can in theory determine with precision any date of the year. A wide variety of avian species that live either in the tropics or in the temperate zone have evolved the ability to measure and respond to seasonal fluctuations in photoperiod (Murton & Westwood 1977;Nicholls et al 1988;Wilson & Donham 1988). Most of our discussion focuses on temperate-zone species, but it should be noted that species in tropical climes can detect even the small changes in day length which occur in this habitat, and photoperiod may play some role in the regulation of reproduction even among birds from this region (Hau 2001).…”

Section: Basics Of the Environmental Regulation Of Annual Cycles In Bmentioning

confidence: 99%

Sex differences in the response to environmental cues regulating seasonal reproduction in birds

Ball

Ketterson

2007

Phil. Trans. R. Soc. B

194

161

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Although it is axiomatic that males and females differ in relation to many aspects of reproduction related to physiology, morphology and behaviour, relatively little is known about possible sex differences in the response to cues from the environment that control the timing of seasonal breeding. This review concerns the environmental regulation of seasonal reproduction in birds and how this process might differ between males and females. From an evolutionary perspective, the sexes can be expected to differ in the cues they use to time reproduction. Female reproductive fitness typically varies more as a function of fecundity selection, while male reproductive fitness varies more as a function sexual selection. Consequently, variation in the precision of the timing of egg laying is likely to have more serious fitness consequences for females than for males, while variation in the timing of recrudescence of the male testes and accompanying territory establishment and courtship are likely to have more serious fitness consequences for males. From the proximate perspective, sex differences in the control of reproduction could be regulated via the response to photoperiod or in the relative importance and action of supplementary factors (such as temperature, food supply, nesting sites and behavioural interactions) that adjust the timing of reproduction so that it is in step with local conditions. For example, there is clear evidence in several temperate zone avian species that females require both supplementary factors and long photoperiods in order for follicles to develop, while males can attain full gonadal size based on photoperiodic stimulation alone. The neuroendocrine basis of these sex differences is not well understood, though there are many candidate mechanisms in the brain as well as throughout the entire hypothalamo-pituitary-gonadal axis that might be important.

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Section: Basics Of the Environmental Regulation Of Annual Cycles In Bmentioning

confidence: 99%

Sex differences in the response to environmental cues regulating seasonal reproduction in birds

Ball

Ketterson

2007

Phil. Trans. R. Soc. B

194

161

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“…Most seasonally breeding birds studied thus far eventually become absolutely refractory to the stimulatory effects of long days [Nicholls et al, 1988;Wilson and Donham, 1988]. In these species, refractoriness typically correlates with a dramatic decrease in the amount of GnRH in the hypothalamus, as compared to levels in photosensitive and/or photostimulated birds [reviewed in Ball and Hahn, 1997;Hahn et al, 1997].…”

Section: Seasonal Changes In the Gnrh Systemmentioning

confidence: 99%

Seasonal Changes in Brain GnRH Immunoreactivity and Song-Control Nuclei Volumes in an Opportunistically Breeding Songbird

MacDougall‐Shackleton

Deviche

Crain

et al. 2001

Brain Behav Evol

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White-winged crossbills (Loxia leucoptera) are opportunistic breeders that can nest at almost any time of year if there is sufficient food. Other cardueline finches that have been shown to breed on a strictly seasonal schedule become absolutely refractory to the stimulatory effects of long-day photoperiod, dramatically down-regulate hypothalamic gonadotropin-releasing hormone (GnRH), and reduce the volume of several song-control nuclei in autumn. This study examined whether changes in photoperiod modify the GnRH and song-control systems in white-winged crossbills. Adult male and female crossbills were captured and held on a naturally changing photoperiod. Brains of male and female birds were collected in May, October, and January. GnRH content was assessed by immunocytochemistry and the volumes of Nissl-defined song-control nuclei (HVc, Area X, and the robust nucleus of the archistriatum) were reconstructed. In contrast to other cardueline finches, GnRH immunoreactivity was relatively stable across the year, exhibiting only modest seasonal variation. The song control system, on the other hand, exhibited large seasonal changes as well as sex differences. Thus, crossbills appear to maintain hypothalamic GnRH content year round, perhaps to facilitate a rapid response to favorable breeding conditions, even on short days. However, song control nuclei are dramatically affected by photoperiod. Future work should examine these systems in crossbills breeding on short days to compare photoperiod-dependent and -independent effects on neural plasticity.

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“…Here we will examine one particularly familiar and well-studied phenomenon, the termination of reproductive competence despite the persistence of conditions that should be stimulatory. Changing photoperiod has several important effects on seasonally breeding birds (see Farner & Follett 1979;Farner & Gwinner 1980;Nicholls et al 1988;Wilson & Donham 1988). Lengthening days in spring induce rapid development of the gonads to full reproductive competence.…”

Section: Case Study: Absolute Refractoriness In Songbirds In Generalmentioning

confidence: 99%

“…Experimentally, absolute refractoriness has been identified by either of two criteria: (i) gonads spontaneously regress and prebasic plumage moult proceeds without any decline in photoperiod, or (ii) gonadotrophin levels and gonads are unaffected by even longer days (24 L : 0 D in the extreme) once gonads have regressed and moult is advanced (see Hamner 1968;Farner et al 1983;Nicholls et al 1988). During autumn, birds regain photosensitivity and can again respond to long days and other cues (see Farner et al 1983;Nicholls et al 1988;Wilson & Donham 1988;Ball 1993;Sharp 1996;Hahn et al 1997;Wingfield & Farner 1993;Dawson et al 2001). A special form of photorefractoriness, relative refractoriness (see Hamner 1968;Robinson & Follett 1982), reduces but does not eliminate photosensitivity.…”

Section: Case Study: Absolute Refractoriness In Songbirds In Generalmentioning

confidence: 99%

Adaptive specialization, conditional plasticity and phylogenetic history in the reproductive cue response systems of birds

Hahn

MacDougall‐Shackleton

2007

Phil. Trans. R. Soc. B

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Appropriately timed integration of breeding into avian annual cycles is critical to both reproductive success and survival. The mechanisms by which birds regulate timing of breeding depend on environmental cue response systems that regulate both when birds do and do not breed. Despite there being multiple possible explanations for birds' abilities to time breeding appropriately in different environments, and for the distribution of different cue response system characteristics among taxa, many studies infer that adaptive specialization of cue response systems has occurred without explicitly considering the alternatives. In this paper, we make explicit three hypotheses concerning the timing of reproduction and distribution of cue response characteristics among taxa: adaptive specialization; conditional plasticity; and phylogenetic history. We emphasize in particular that although conditional plasticity built into avian cue response systems (e.g. differing rates of gonadal development and differing latencies until onset of photorefractoriness) may lead to maladaptive annual cycles in some novel circumstances, this plasticity also can lead to what appear to be adaptively specialized cue response systems if not viewed in a comparative context. We use a comparative approach to account for the distribution of one important feature of avian reproductive cue response systems, photorefractoriness. Analysis of the distribution within songbirds of one criterion for absolute photorefractoriness, the spontaneous regression of the gonads without any decline in photoperiod, reveals that a failure to display this trait probably represents an adaptive specialization to facilitate a flexible reproductive schedule. More finely resolved analysis of both criteria for absolute photorefractoriness (the second being total lack of a reproductive response even to constant light after gonadal regression has occurred) within the cardueline finches not only provides further confirmation of this interpretation, but also indicates that these two criteria for photorefractoriness can be, and have been, uncoupled in some taxa. We suggest that careful comparative studies at different phylogenetic scales will be extremely valuable for distinguishing between adaptive specialization and non-adaptive explanations, such as phylogenetic history as explanations of cue response traits in particular taxa. We also suggest that particular focus on taxa in which individuals may breed on very different photoperiods (latitudes or times of year) in different years should be particularly valuable in identifying the range of environmental conditions across which conditionally plastic cue responses can be adaptive.

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Daylength and Control of Seasonal Reproduction in Male Birds

Cited by 34 publications

References 71 publications

Sex differences in the response to environmental cues regulating seasonal reproduction in birds

Sex differences in the response to environmental cues regulating seasonal reproduction in birds

Seasonal Changes in Brain GnRH Immunoreactivity and Song-Control Nuclei Volumes in an Opportunistically Breeding Songbird

Adaptive specialization, conditional plasticity and phylogenetic history in the reproductive cue response systems of birds

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