Breaking down seasonality: Androgen modulation and stress response in a highly stable environment

González-Gómez, Paulina L.; Merrill, Loren; Ellis, Vincenzo A.; Venegas, Cristóbal I.; Pantoja, Javiera I.; Vásquez, Rodrigo A.; Wingfield, John C.

doi:10.1016/j.ygcen.2013.05.007

Cited by 14 publications

(36 citation statements)

References 75 publications

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“…At AR where birds would experience lower energetic demands due to stable biotic and abiotic conditions, we predicted much less temporal organization of LHSs as found by Gonzalez‐Gomez et al. (). If rufous‐collared sparrows are affected by seasonality in these environments, and AR represents a less energetic demanding locality, we expected to confirm previous data (Gonzalez‐Gomez et al., ) on year‐round breeding and moult (and overlap of both cycles) in the highly aseasonal AR population, and find a strong temporal division of the annual LHSs in the highly seasonal FJ.…”

Section: Introductionsupporting

confidence: 52%

“…The endocrine system is important for coordinating physiological, behavioural and morphological changes, and its activity is linked to environmental conditions (Gonzalez‐Gomez et al., ). Corticosterone (CORT), the main glucocorticoid in birds, at baseline levels contributes to the regulation of basic metabolic functions such as protein and lipid metabolism, water balance and glucose provisioning to cells (Landys, Ramenofsky, Guglielmo, & Wingfield, ).…”

Section: Introductionmentioning

confidence: 99%

“…(). If rufous‐collared sparrows are affected by seasonality in these environments, and AR represents a less energetic demanding locality, we expected to confirm previous data (Gonzalez‐Gomez et al., ) on year‐round breeding and moult (and overlap of both cycles) in the highly aseasonal AR population, and find a strong temporal division of the annual LHSs in the highly seasonal FJ. We predicted better body condition variables (i.e., body condition index, parasite load, muscle development, fat storage, haematocrit percentage), higher levels of baseline and stress‐induced levels of CORT, higher T and higher degree of seasonal variation in hormone levels in FJ compared to AR.…”

Section: Introductionmentioning

confidence: 99%

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Contrasting seasonal and aseasonal environments across stages of the annual cycle in the rufous‐collared sparrow, Zonotrichia capensis: Differences in endocrine function, proteome and body condition

González-Gómez

Echeverrı́a

Estades

et al. 2018

Journal of Animal Ecology

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The timing and duration of life-history stages (LHSs) within the annual cycle can be affected by local environmental cues which are integrated through endocrine signalling mechanisms and changes in protein function. Most animals express a single LHS within a given period of the year because synchronous expression of LHSs is thought to be too costly energetically. However, in very rare and extremely stable conditions, breeding and moult have been observed to overlap extensively in rufous-collared sparrows (Zonotrichia capensis) living in valleys of the Atacama Desert-one of the most stable and aseasonal environments on Earth. To examine how LHS traits at different levels of organization are affected by environmental variability, we compared the temporal organization and duration of LHSs in populations in the Atacama Desert with those in the semiarid Fray Jorge National Park in the north of Chile-an extremely seasonal climate but with unpredictable droughts and heavy rainy seasons. We studied the effects of environmental variability on morphological variables related to body condition, endocrine traits and proteome. Birds living in the seasonal environment had a strict temporal division of LHSs, while birds living in the aseasonal environment failed to maintain a temporal division of LHSs resulting in direct overlap of breeding and moult. Further, higher circulating glucocorticoids and androgen concentrations were found in birds from seasonal compared to aseasonal populations. Despite these differences, body condition variables and protein expression were not related to the degree of seasonality but rather showed a strong relationship with hormone levels. These results suggest that animals adjust to their environment through changes in behavioural and endocrine traits and may be limited by less labile traits such as morphological variables or expression of specific proteins under certain circumstances. These data on free-living birds shed light on how different levels of life-history organization within an individual are linked to increasing environmental heterogeneity.

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Section: Introductionsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Contrasting seasonal and aseasonal environments across stages of the annual cycle in the rufous‐collared sparrow, Zonotrichia capensis: Differences in endocrine function, proteome and body condition

González-Gómez

Echeverrı́a

Estades

et al. 2018

Journal of Animal Ecology

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“…Although breeding T levels are often reported to be 2–4ng/ml for this species [Moore et al, 2004c; Addis et al, 2010; González-Gómez et al, 2013], these values are population averages that can obscure individual high values [Williams, 2008; Hau et al, 2008]. Consistent with this, Moore et al [2004b] found that the average T concentration for 35 breeding male rufous-collared sparrows was 4 ng/ml.…”

Section: Discussionmentioning

confidence: 73%

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Small

Brenowitz²,

Wojtenek

et al. 2015

Brain Behav Evol

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In mid- to high-latitude songbirds, seasonal reproduction is stimulated by increasing day length accompanied by elevated plasma sex steroid levels, increased singing, and growth of the song control nuclei (SCN). Plasticity of the SCN and song behavior are primarily mediated by testosterone (T) and its metabolites in most species studied thus far. However, the majority of bird species are tropical and have less pronounced seasonal reproductive cycles. We have previously documented that equatorial rufous-collared sparrows (Zonotrichia capensis) exhibit seasonal neuroplasticity in the SCN. Manipulating T in these birds, however, did not alter singing behavior. In the current study, we investigated whether T mediates plasticity of the SCN in a similar manner to temperate songbirds. In the first experiment, we treated captive male birds with T or blank implants during the nonbreeding season. In a second experiment, we treated captive male birds with either blank implants, T-filled implants, T with flutamide (FLU; an androgen receptor antagonist) or T with FLU and 1,4,6-androstatriene-3,17-dione (ATD; an estrogen synthesis inhibitor) during the breeding season. In both experiments, the volumes of the brain areas high vocal center (HVC), Area X, and robust nucleus of the arcopallium (RA) were measured along with singing behavior. In summary, T stimulated growth of HVC and RA, and the combined effect of FLU and ATD reversed this effect in HVC. Area X was not affected by T treatment in either experiment. Neither T-treated birds nor controls sang in captivity during either experiment. Together, these data indicate that T mediates seasonal changes in the HVC and RA of both tropical and higher- latitude bird species even if the environmental signals differ. However, unlike most higher-latitude songbirds, we found no evidence that motivation to sing or growth of Area X are stimulated by T under captive conditions.

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“…Knowledge of these CORT levels for the birds under study is essential, as intraspecific CORT levels may vary substantially between populations. For example, rufouscrowned sparrows moulting in Chile had stress-induced CORT levels nearly 5 times higher while breeding and 6.5 times higher while moulting than a population studied in Ecuador (Gonzalez-Gomez et al, 2013;Wada et al, 2006), although the extent to which these disparities reflect differences in antibodies used in these assays is unknown. In addition to experimentally manipulating CORT levels, the experiment would further benefit from also varying nutrition.…”

Section: Speciesmentioning

confidence: 97%

Lack of seasonal and moult-related stress modulation in an opportunistically breeding bird: The white-plumed honeyeater (Lichenostomus penicillatus)

Buttemer

Addison

Astheimer

2015

Hormones and Behavior

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Breaking down seasonality: Androgen modulation and stress response in a highly stable environment

Cited by 14 publications

References 75 publications

Contrasting seasonal and aseasonal environments across stages of the annual cycle in the rufous‐collared sparrow, Zonotrichia capensis: Differences in endocrine function, proteome and body condition

Contrasting seasonal and aseasonal environments across stages of the annual cycle in the rufous‐collared sparrow, Zonotrichia capensis: Differences in endocrine function, proteome and body condition

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Lack of seasonal and moult-related stress modulation in an opportunistically breeding bird: The white-plumed honeyeater (Lichenostomus penicillatus)

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