Seasonal Rhythms

Romero, L. Michael; Bauer, Carolyn M.; Bruijn, Robert de; Lattin, Christine R.

doi:10.1016/b978-0-12-802175-0.00042-5

Cited by 9 publications

(4 citation statements)

References 32 publications

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“…In this case, GC levels may be lower where challenges are likely to be frequent or prolonged and during life-history stages where the costs of high GCs may be particularly severe. To our knowledge, a similar framework has not previously been applied to macroevolutionary patterning in GCs; however, the framework developed here has some consistencies with hypotheses proposed to explain seasonal changes in GCs (e.g., the preparative and energy mobilization hypotheses vs. the behavioral hypothesis; Romero 2002;Romero et al 2017) and with hypotheses about GC-fitness relationships within populations (Wingfield et al 1998;Bonier et al 2009a;Schoenle et al 2018).…”

Section: Introductionmentioning

confidence: 90%

Macroevolutionary Patterning in Glucocorticoids Suggests Different Selective Pressures Shape Baseline and Stress-Induced Levels

Vitousek

Johnson

Downs

et al. 2019

The American Naturalist

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Glucocorticoid (GC) hormones are important phenotypic mediators across vertebrates, but their circulating concentrations can vary markedly. Here we investigate macroevolutionary patterning in GC levels across tetrapods by testing seven specific hypotheses about GC variation and evaluating whether the supported hypotheses reveal consistent patterns in GC evolution. If selection generally favors the "supportive" role of GCs in responding effectively to challenges, then baseline and/or stress-induced GCs may be higher in challenging contexts. Alternatively, if selection generally favors "protection" from GCinduced costs, GCs may be lower in environments where challenges are more common or severe. The predictors of baseline GCs were all consistent with supportive effects: levels were higher in smaller organisms and in those inhabiting more energetically demanding environments. During breeding, baseline GCs were also higher in populations and species with fewer lifetime opportunities to reproduce. The predictors of stress-induced GCs were instead more consistent with the protection hypothesis: during breeding, levels were lower in organisms with fewer lifetime reproductive opportunities. Overall, these patterns indicate a surprising degree of consistency in how some selective pressures shape GCs across broad taxonomic scales; at the same time, in challenging environments selection appears to operate on baseline and stress-induced GCs in distinct ways.

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Section: Introductionmentioning

confidence: 90%

Macroevolutionary Patterning in Glucocorticoids Suggests Different Selective Pressures Shape Baseline and Stress-Induced Levels

Vitousek

Johnson

Downs

et al. 2019

The American Naturalist

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“…An associated column provides information about whether the sampled individuals were confirmed to be in a given life history stage (e.g., incubating birds captured off their nests), or whether the life history stage reflected the typical stage for individuals in that population at the time of sampling (e.g., birds sampled in mist nets during the breeding season but not traced to a specific nest). For birds, information on moult status was also recorded as provided 35 .…”

Section: Methodsmentioning

confidence: 99%

HormoneBase, a population-level database of steroid hormone levels across vertebrates

et al. 2018

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Hormones are central regulators of organismal function and flexibility that mediate a diversity of phenotypic traits from early development through senescence. Yet despite these important roles, basic questions about how and why hormone systems vary within and across species remain unanswered. Here we describe HormoneBase, a database of circulating steroid hormone levels and their variation across vertebrates. This database aims to provide all available data on the mean, variation, and range of plasma glucocorticoids (both baseline and stress-induced) and androgens in free-living and un-manipulated adult vertebrates. HormoneBase (www.HormoneBase.org) currently includes >6,580 entries from 476 species, reported in 648 publications from 1967 to 2015, and unpublished datasets. Entries are associated with data on the species and population, sex, year and month of study, geographic coordinates, life history stage, method and latency of hormone sampling, and analysis technique. This novel resource could be used for analyses of the function and evolution of hormone systems, and the relationships between hormonal variation and a variety of processes including phenotypic variation, fitness, and species distributions.

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“…Romero et al [ 26 ] tested this hypothesis on few rodent species and found that glucocorticoid concentrations were lower in the fall in species relying upon endogenous fat reserves during hibernation, but higher in species that cache food to survive winter. Nevertheless, most studies provide clear evidence that, although following different patterns, a majority of reptilian, amphibian, avian, and mammalian species seasonally modulate glucocorticoid concentrations [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Losing seasonal patterns in a hibernating omnivore? Diet quality proxies and faecal cortisol metabolites in brown bears in areas with and without artificial feeding

Sergiel¹,

Barja²,

Navarro-Castilla³

et al. 2020

PLoS ONE

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Bears are omnivores particularly well-adapted to variations in the nutritional composition, quality and availability of food resources. Artificial feeding practices have been shown to strongly influence diet composition and seasonality, as well as to cause alterations in wintering and movement in brown bears (Ursus arctos). In this study, we investigated seasonal differences (hypophagia vs hyperphagia) in food quality of two brown bear subpopulations in the Polish Carpathians using faecal nitrogen (FN) and carbon (FC) estimates. The subpopulations inhabit areas that differ in artificial feeding practices: no artificial feeding occurs in the western subpopulation (Tatra Mountains), while artificial food targeted to ungulates is provided and used year-round in the eastern subpopulation (Bieszczady Mountains). We also compared these results with faecal cortisol metabolites (FCM) to explore how FN and FC correlate with the hypothalamic-pituitary-adrenal axis activity and if the seasonal patterns are apparent. We found that in Tatra Mts bears fed on significantly higher quality diet, as shown by FN and FC values, and had significantly higher FC levels in hyperphagia, when they accumulate fat reserves for wintering. The pattern in FCM levels for Tatra subpopulation followed the changes in energy intake during the seasons of hypo- and hyperphagia, while in Bieszczady Mts, the area with intensive feeding, no seasonal patterns could be observed. Artificial feeding practices may disrupt nutrient phenology and seasonality, relative to subpopulations with natural diets. We showed that the availability of human-provided foods may alter not only the overall dietary quality, but also hormonal patterns linked to seasonal nutritional requirements. Combining FN, FC and FCM proved to be a useful tool for reconstructing diet quality and related physiological patterns.

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Seasonal Rhythms

Cited by 9 publications

References 32 publications

Macroevolutionary Patterning in Glucocorticoids Suggests Different Selective Pressures Shape Baseline and Stress-Induced Levels

Macroevolutionary Patterning in Glucocorticoids Suggests Different Selective Pressures Shape Baseline and Stress-Induced Levels

HormoneBase, a population-level database of steroid hormone levels across vertebrates

Losing seasonal patterns in a hibernating omnivore? Diet quality proxies and faecal cortisol metabolites in brown bears in areas with and without artificial feeding

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