Infection-nutrition feedbacks: fat supports pathogen clearance but pathogens reduce fat in a wild mammal.

Though far less obvious than direct effects (clinical disease or mortality), the indirect influences of pathogens are difficult to estimate but may hold fitness consequences. Here, we disentangle the directional relationships between infection and energetic reserves, evaluating the hypotheses that energetic reserves influence infection status of the host and that infection elicits costs to energetic reserves. Using repeated measures of fat reserves and infection status in individual bighorn sheep () in the Greater Yellowstone Ecosystem, we documented that fat influenced ability to clear pathogens () and infection with respiratory pathogens was costly to fat reserves.

Pathology of Chronic Mycoplasma ovipneumoniae Carriers in a Declining Bighorn Sheep (Ovis canadensis) Population.

Bighorn sheep (Ovis canadensis) across North America commonly experience population-limiting epizootics of respiratory disease. Although many cases of bighorn sheep pneumonia are polymicrobial, Mycoplasma ovipneumoniae is most frequently associated with all-age mortality events followed by years of low recruitment. Chronic carriage of M.

Behavioural responses of a large, heat-sensitive mammal to climatic variation at multiple spatial scales.

Climate warming creates energetic challenges for endothermic species by increasing metabolic and hydric costs of thermoregulation. Although endotherms can invoke an array of behavioural and physiological strategies for maintaining homeostasis, the relative effectiveness of those strategies in a climate that is becoming both warmer and drier is not well understood. In accordance with the heat dissipation limit theory which suggests that allocation of energy to growth and reproduction by endotherms is constrained by the ability to dissipate heat, we expected that patterns of habitat use by large, heat-sensitive mammals across multiple scales are critical for behavioural thermoregulation during periods of potential heat stress and that they must invest a large portion of time to maintain heat balance.

Biomarkers of Animal Nutrition: From Seasonal to Lifetime Indicators of Environmental Conditions.

Nutrition underpins survival and reproduction in animal populations; reliable nutritional biomarkers are therefore requisites to understanding environmental drivers of population dynamics. Biomarkers vary in scope of inference and sensitivity, making it important to know what and when to measure to properly quantify biological responses. We evaluated the repeatability of three nutritional biomarkers in a large, iteroparous mammal to evaluate the level of intrinsic and extrinsic contributions to those traits.