Island Living Indirectly Affects Hair Glucocorticoid Levels in a Small Mammal.

AbstractIsland vertebrates that are small on the mainland tend to be larger and exhibit tamer behavior than their mainland conspecifics-a combined set of characteristics known as "island syndrome." Such island-specific traits are often attributed to lower predation pressure on islands than on the mainland. While the morphology and behavior of island vertebrates has received significant attention, relatively few studies have compared physiological traits between island and mainland populations.

Endotherms trade body temperature regulation for the stress response.

Responding to perceived threats is energetically expensive and can require animals to curtail somatic repair, immunity, and even reproduction to balance energy ledgers. In birds and mammals, energetic demands of thermoregulation are often immense, yet whether homeostatic body temperatures are also compromised to aid the stress response is not known. Using data sourced from over 60 years of literature and 24 endotherm species, we show that exposure to non-thermal challenges (e.

Within-Generation and Transgenerational Plasticity of a Temperate Salmonid in Response to Thermal Acclimation and Acute Temperature Stress.

AbstractThe rise in temperature associated with climate change may threaten the persistence of stenothermal organisms with limited capacities for beneficial thermal acclimation. We investigated the capacity for within-generation and transgenerational thermal responses in brook trout (), a cold-adapted salmonid. Adult fish were acclimated to temperatures within (10°C) and above (21°C) their thermal optimum for 6 mo before spawning, then mated in a full factorial breeding design to produce offspring from cold- and warm-acclimated parents and bidirectional crosses between parents from both temperature treatments.

Using mass spectrometry to investigate fluorescent compounds in squirrel fur.

While an array of taxa are capable of producing fluorescent pigments, fluorescence in mammals is a novel and poorly understood phenomenon. A first step towards understanding the potential adaptive functions of fluorescence in mammals is to develop an understanding of fluorescent compounds, or fluorophores, that are present in fluorescent tissue. Here we use Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) of flying squirrel fur known to fluoresce under ultraviolet (UV) light to identify potentially fluorescent compounds in squirrel fur.

Changes in Body Surface Temperature Play an Underappreciated Role in the Avian Immune Response.

AbstractFever and hypothermia are well-characterized components of systemic inflammation. However, our knowledge of the mechanisms underlying such changes in body temperature is largely limited to rodent models and other mammalian species. In mammals, high dosages of an inflammatory agent (e.

New migration and distribution patterns of Atlantic walruses () around Nunavik (Québec, Canada) identified using Inuit Knowledge.

Unlabelled: Environmental changes are affecting the Arctic at an unprecedented rate, but limited scientific knowledge exists on their impacts on species such as walruses (). Inuit Traditional and Local Ecological Knowledge (Inuit TEK/LEK) held by Inuit walrus harvesters could shed light on walrus ecology and related environmental changes. Our main objective was to study spatial and temporal changes in Atlantic walrus () distribution in Nunavik (northern Québec, Canada) using Inuit TEK/LEK.

Body temperature is a repeatable trait in a free-ranging passerine bird.

Body temperature (Tb) affects animal function through its influence on rates of biochemical and biophysical reactions, the molecular structures of proteins and tissues, and, ultimately, organismal performance. Despite its importance in driving physiological processes, there are few data on how much variation in Tb exists within populations of organisms, and whether this variation consistently differs among individuals over time (i.e.

Infrared thermography as a technique to measure physiological stress in birds: Body region and image angle matter.

In vertebrates, changes in surface temperature following exposure to an acute stressor are thought to be promising indicators of the physiological stress response that may be captured noninvasively by infrared thermography. However, the efficacy of using stress-induced changes in surface temperature as indicators of physiological stress-responsiveness requires: (1) an understanding of how such responses vary across the body, (2) a magnitude of local, stress-induced thermal responses that is large enough to discriminate and quantify differences among individuals with conventional technologies, and (3) knowledge of how susceptible measurements across different body regions are to systematic error. In birds, temperature of the bare tissues surrounding the eye (the periorbital, or "eye," region) and covering the bill have each been speculated as possible predictors of stress physiological state.

Limited transgenerational effects of environmental temperatures on thermal performance of a cold-adapted salmonid.

The capacity of ectotherms to cope with rising temperatures associated with climate change is a significant conservation concern as the rate of warming is likely too rapid to allow for adaptative responses in many populations. Transgenerational plasticity (TGP), if present, could potentially buffer some of the negative impacts of warming on future generations. We examined TGP in lake trout to assess their inter-generational potential to cope with anticipated warming.

Experimental evidence that hyperthermia limits offspring provisioning in a temperate-breeding bird.

In many vertebrates, parental care can require long bouts of daily exercise that can span several weeks. Exercise, especially in the heat, raises body temperature, and can lead to hyperthermia. Typical strategies for regulating body temperature during endurance exercise include modifying performance to avoid hyperthermia (anticipatory regulation) and allowing body temperature to rise above normothermic levels for brief periods of time (facultative hyperthermia).

Maternal glucocorticoid levels during incubation predict breeding success, but not reproductive investment, in a free-ranging bird.

The hormone corticosterone (CORT) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. The 'CORT-fitness hypothesis' proposes that high levels of CORT arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). In contrast, the CORT-adaptation hypothesis suggests that, during energetically demanding periods, CORT will mediate physiological or behavioral changes that result in increased reproductive investment and success (a positive relationship).

Social hierarchy reveals thermoregulatory trade-offs in response to repeated stressors.

Coping with stressors can require substantial energetic investment, and when resources are limited, such investment can preclude simultaneous expenditure on other biological processes. Among endotherms, energetic demands of thermoregulation can also be immense, yet our understanding of whether a stress response is sufficient to induce changes in thermoregulatory investment is limited. Using the black-capped chickadee as a model species, we tested a hypothesis that stress-induced changes in surface temperature (), a well-documented phenomenon across vertebrates, stem from trade-offs between thermoregulation and stress responsiveness.

Heat dissipation capacity influences reproductive performance in an aerial insectivore.

Climatic warming is predicted to increase the frequency of extreme weather events, which may reduce an individual's capacity for sustained activity because of thermal limits. We tested whether the risk of overheating may limit parental provisioning of an aerial insectivorous bird in population decline. For many seasonally breeding birds, parents are thought to operate close to an energetic ceiling during the 2-3 week chick-rearing period.

Reframing conservation physiology to be more inclusive, integrative, relevant and forward-looking: reflections and a horizon scan.

Applying physiological tools, knowledge and concepts to understand conservation problems (i.e. conservation physiology) has become commonplace and confers an ability to understand mechanistic processes, develop predictive models and identify cause-and-effect relationships.

No island-effect on glucocorticoid levels for a rodent from a near-shore archipelago.

Island rodents are often larger and live at higher population densities than their mainland counterparts, characteristics that have been referred to as "island syndrome". Island syndrome has been well studied, but few studies have tested for island-mainland differences in stress physiology. We evaluated island syndrome within the context of stress physiology of white-footed mice () captured from 11 islands and five mainland sites in Thousand Islands National Park, Ontario, Canada.

Evidence that stress-induced changes in surface temperature serve a thermoregulatory function.

The fact that body temperature can rise or fall following exposure to stressors has been known for nearly two millennia; however, the functional value of this phenomenon remains poorly understood. We tested two competing hypotheses to explain stress-induced changes in temperature, with respect to surface tissues. Under the first hypothesis, changes in surface temperature are a consequence of vasoconstriction that occur to attenuate blood loss in the event of injury and serve no functional purpose per se; defined as the 'haemoprotective hypothesis'.

Exposure of Avian Embryos to Cycling Incubation Temperatures Reduces Adult Bactericidal Ability.

In birds, the temperature at which eggs are incubated shapes many aspects of hatchling phenotype, but long-term effects are less studied. We studied the effect of incubation temperature and pattern on the subsequent development of innate immune function in Japanese quail (). We incubated quail eggs in one of three replicated treatments: control (37.

Metabolic rates of embryos and alevin from a cold-adapted salmonid differ with temperature, population and family of origin: implications for coping with climate change.

Early developmental stages of cold-adapted ectotherms such as brook trout () are at higher risk of mortality with increasing water temperatures. To determine the amount of variation present in early life, which may allow for potential adaptation to increasing temperature, we examined the routine metabolic rates (RMR) of wild-origin brook trout embryos and alevins reared at normal (5°C) and elevated (9°C) temperatures. The experiment was structured to examine variation in RMR within and among several levels of biological organization (family, population and ancestral type (native vs.

Seasonal changes in acute stressor-mediated plasma glucocorticoid regulation in New World flying squirrels.

Southern flying squirrels have higher circulating cortisol levels than most vertebrates. However, regulation of tissue exposure to cortisol by the hormone's carrier protein, corticosteroid-binding globulin (CBG), appears to be altered due to lower-than-expected CBG expression levels, and a reduced affinity for cortisol. To assess the capacity of flying squirrels to regulate acute stress-mediated cortisol levels, we used the dexamethasone (DEX) suppression test followed by the adrenocorticotropic hormone (ACTH) stimulation test in both the breeding and non-breeding seasons, and quantified resultant changes in plasma cortisol and relative CBG levels.

Maternal immunization increases nestling energy expenditure, immune function, and fledging success in a passerine bird.

Female birds transfer maternally derived antibodies (matAb) to their nestlings, via the egg yolk. These antibodies are thought to provide passive protection, and allow nestlings to avoid the costs associated with mounting an innate immune response. To test whether there is an energetic benefit to nestlings from receiving matAb, we challenged adult female tree swallows () prior to clutch initiation with either lipopolysaccharide (LPS) or saline (Control).

Acclimation capacity of the cardiac HSP70 and HSP90 response to thermal stress in lake trout (Salvelinus namaycush), a stenothermal ice-age relict.

The ability of cold-adapted species to persist in the face of climate change will depend on the capacity of individuals for thermal acclimation, adaptation, and the degree of physiological variation that exists among populations. We tested the acclimation capacity of cardiac HSP70 and HSP90 in four populations of lake trout (Salvelinus namaycush), a cold-adapted salmonid. We acclimated fish to four temperatures (8°C, 11°C, 15°C, and 19°C) and measured cardiac HSP70 and HSP90 levels by western blot prior to and following an acute (1h) heat shock at 23°C.