Temporal Flexibility in Avian Reproduction

Hahn, Thomas P.; Boswell, Timothy; Wingfield, John C.; Ball, Gregory F.

doi:10.1007/978-1-4757-9915-6_2

Cited by 115 publications

(130 citation statements)

References 94 publications

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“…Not all species exhibit such variation in GnRH content in relation to reproductive state (see Ball and Hahn, 1997, Dawson et al, 2001, Pereyra et al, 2005. Initially it appeared as if the degree of seasonal GnRH plasticity was associated with variation in the onset of photorefractoriness (Ball andHahn, 1997, Hahn et al, 1997), but recent work has defined a set of general rules influencing plasticity (Pereyra et al 2005). In particular, comparative studies of cardueline finches with diverse photoperiod response patterns suggest that GnRH plasticity tends to be observed in species that do exhibit gonadal regression while still experiencing long daylengths that were previously able to stimulate gonadal growth (Pereyra et al 2005, Macdougall-Shackleton et al, 2006.…”

Section: Seasonal Changes In the Gnrh In Relation To Variation In Brementioning

confidence: 99%

Photoperiodic induced changes in reproductive state of border canaries (Serinus canaria) are associated with marked variation in hypothalamic gonadotropin-releasing hormone immunoreactivity and the volume of song control regions

Hurley¹,

Wallace²,

Sartor³

et al. 2008

General and Comparative Endocrinology

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In temperate zone songbirds, such as canaries (Serinus canaria), seasonal variation in gonadal activity and behavior are associated with marked brain changes. These include gonadotropinreleasing hormone (GnRH) expression and the volume of brain areas controlling song production. Questions have been raised about the consistency of seasonal brain changes in canaries. Laboratory studies of the American singer strain raised doubts as to whether this strain exhibits a robust photoperiodic response along with changes in brain GnRH content, and studies of free-living canaries have failed to identify seasonal changes in volume of song control nuclei. We assessed differences in brain GnRH and the song control system associated with photoperiod-induced variation in reproductive state in Border canaries. We found that males and females maintained for 10 weeks on long days (14L:10D) regress their gonads, exhibit a decline in testosterone and initiate molt; a response consistent with the onset of absolute photorefractoriness (i.e., failed to respond to previously stimulating daylengths). All birds regained photosensitivity (i.e., exhibited gonadal response to stimulating daylengths) after experiencing short days (8L:16D) for 6 weeks. Furthermore, comparisons of birds in either a photosensitive, photostimulated, or photorefractory state revealed a marked increase in GnRH protein expression in the photosensitive and photostimulated birds over photorefractory birds. A similar variation was observed in the volume of key forebrain song nuclei. Thus, Border canaries demonstrate measurable neuroplasticity in response to photoperiodic manipulations. These data, along with previous work on other strains of canaries, indicate the presence of intra-specific variation in photoperiodically regulated neuroplasticity.

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Section: Seasonal Changes In the Gnrh In Relation To Variation In Brementioning

confidence: 99%

Photoperiodic induced changes in reproductive state of border canaries (Serinus canaria) are associated with marked variation in hypothalamic gonadotropin-releasing hormone immunoreactivity and the volume of song control regions

Hurley¹,

Wallace²,

Sartor³

et al. 2008

General and Comparative Endocrinology

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“…Although large changes in behavior, gonadal physiology, and peripheral endocrine physiology occur in a variety of animals, birds are unusual in the degree to which these changes can be underlain by similarly dramatic changes within the neuroendocrine machinery itself. During absolute photorefractoriness, the down-regulation of the septo-infundibular GnRH system is profound Hahn et al, 1997;Dawson et al, 2001). In the few temperate zone taxa that do not become absolutely photorefractory (i.e., Japanese quail, crossbills; Robinson and Follett, 1982;Hahn et al, 2004), down-regulation of the GnRH system does not occur, even though the birds may be relatively refractory (Foster et al, 1987;Pereyra et al, in press; see Nicholls et al, 1988).…”

Section: Photoperiodic Statesmentioning

confidence: 99%

“…In the few temperate zone taxa that do not become absolutely photorefractory (i.e., Japanese quail, crossbills; Robinson and Follett, 1982;Hahn et al, 2004), down-regulation of the GnRH system does not occur, even though the birds may be relatively refractory (Foster et al, 1987;Pereyra et al, in press; see Nicholls et al, 1988). Stimulation of the reproductive axis can enhance activity of the GnRH system (e.g., Saldanha et al, 1994a), but the most pronounced changes occur during development and dissipation of absolute refractoriness Hahn et al, 1997;Sharp, 1996).…”

Section: Photoperiodic Statesmentioning

confidence: 99%

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Goodson

Saldanha

Hahn

et al. 2005

Hormones and Behavior

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Ever since investigations in the field of behavioral endocrinology were hatched with experiments on roosters, birds have provided original insights into issues of fundamental importance for all vertebrate groups. Here we focus on more recent advances that continue this tradition, including 1) environmental regulation of neuroendocrine and behavioral systems, 2) steroidogenic enzyme functions that are related to intracrine processes and de novo production of neurosteroids, and 3) hormonal regulation of neuroplasticity. We also review recent findings on the anatomical and functional organization of steroid-sensitive circuits in the basal forebrain and midbrain. A burgeoning body of data now demonstrates that these circuits comprise an evolutionarily conserved network, thus numerous novel insights obtained from birds can be used (in a relatively straightforward manner) to generate predictions for other taxa as well. We close by using birdsong as an example that links these areas together, thereby highlighting the exceptional opportunities that birds offer for integrative studies of behavioral neuroendocrinology, and behavioral biology in general. Keywords aggression; reproduction; song; limbic system; vasotocin; photoperiod; neurosteroid; DHEA; aromatase; adult neurogenesis; estrogen; testosterone; thyroxin; hypothalamus; hippocampus; HVC; septum; GnRH; SCN; season; neuroplasticity Birds offer excellent opportunities for behavioral and neuroendocrine experiments in both the field and the laboratory, and studies conducted at this interface have historically placed avian models on the cutting edge of research (Konishi et al., 1989; also see Wingfield, this issue). Indeed, wild birds offer a combination of accessibility (being diurnal and terrestrial) and diversity (social and ecological) that makes them invaluable models for studying mechanistic and evolutionary questions that are not as tractable in other vertebrate groups. This diversity can be studied within the context of neural and endocrine systems that share many features with those of other taxa (thereby increasing the general relevance of avian studies) (Goodson, 2005), although these features are often more pronounced in birds. Such examples include exceptionally robust and widespread neural aromatase activity, and adult neurogenesis in the forebrain, both of which are considered further below (also see Ball and Balthazart, 2004;

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“…Ultimate factors, such as food availability, weather, competition or predation, favor individuals that reproduce when changes in the environment occur. Therefore, animals must prepare for changes in the environment by responding to proximate cues, which are features of the environment that actually influence physiology or behavior (Hahn et al, 1997). Proximate cues can be predictive, such as changes in photoperiod (Wingfield, 1983), or supplementary, such as changes in weather (Hahn et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, animals must prepare for changes in the environment by responding to proximate cues, which are features of the environment that actually influence physiology or behavior (Hahn et al, 1997). Proximate cues can be predictive, such as changes in photoperiod (Wingfield, 1983), or supplementary, such as changes in weather (Hahn et al, 1997). Predictive cues help regulate sex steroids production, which in turn, regulates reproductive behaviors in a variety of taxa including birds (Noble, 1973;Delville and Balthazart, 1987;Ball and Balthazart, 2002), fish (Tricas et al, 2000, Grober andBass, 2002), mammals (Hull et al, 2002;Blaustein and Erskine, 2002), reptiles (Alderete et al, 1980;Rhen et al, 1999;Godwin and Crews, 2002) and amphibians (Diakow and Nemiroff, 1981;Schmidt, 1984Schmidt, , 1985Mendonça et al, 1985;Boyd, 1994, Wilczynski and.…”

Section: Introductionmentioning

confidence: 99%

Social regulation of plasma estradiol concentration in a female anuran

Lynch

Wilczynski

2006

Hormones and Behavior

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The behavior of an individual within a social aggregation profoundly influences behavior and physiology of other animals within the aggregation in such a way that these social interactions can enhance reproductive success, survival and fitness. This phenomenon is particularly important during the breeding season when males and female must synchronize their reproductive efforts. We examined whether exposure to conspecific social cues can elevate sex steroid levels, specifically estradiol and androgens, in female túngara frogs (Physalaemus pustulosus). We compared plasma estradiol and androgen concentrations in wild-caught females before and after exposure to either natural mate choruses or random tones. After exposure to mate choruses for 10 consecutive nights, estradiol concentrations were significantly elevated whereas there was no significant elevation in estradiol concentrations in the group of females exposed to random tones for 10 nights. Plasma androgen concentrations were not significantly changed after exposure to either natural mate choruses or random tones for 10 consecutive nights. Social modulation of estradiol concentrations may be important in maintaining a female's reproductive state while males are chorusing. To our knowledge, this is the first study to demonstrate social regulation of estradiol concentration in female anurans.

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Temporal Flexibility in Avian Reproduction

Cited by 115 publications

References 94 publications

Photoperiodic induced changes in reproductive state of border canaries (Serinus canaria) are associated with marked variation in hypothalamic gonadotropin-releasing hormone immunoreactivity and the volume of song control regions

Photoperiodic induced changes in reproductive state of border canaries (Serinus canaria) are associated with marked variation in hypothalamic gonadotropin-releasing hormone immunoreactivity and the volume of song control regions

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Social regulation of plasma estradiol concentration in a female anuran

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