Biomarkers of animal health: integrating nutritional ecology, endocrine ecophysiology, ecoimmunology, and geospatial ecology

Abstract

Diverse biomarkers including stable isotope, hormonal, and ecoimmunological assays are powerful tools to assess animal condition. However, an integrative approach is necessary to provide the context essential to understanding how biomarkers reveal animal health in varied ecological conditions. A barrier to such integration is a general lack of awareness of how shared extraction methods from across fields can provide material from the same animal tissues for diverse biomarker assays. In addition, the use of shared methods for extracting differing tissue fractions can also provide biomarkers for how animal health varies across time. Specifically, no study has explicitly illustrated the depth and breadth of spacial and temporal information that can be derived from coupled biomarker assessments on two easily collected tissues: blood and feathers or hair. This study used integrated measures of glucocorticoids, stable isotopes, and parasite loads in the feathers and blood of fall-migrating Northern saw-whet owls (Aegolius acadicus) to illustrate the wealth of knowledge about animal health and ecology across both time and space. In feathers, we assayed deuterium (δD) isotope and corticosterone (CORT) profiles, while in blood we measured CORT and blood parasite levels. We found that while earlier migrating owls had elevated CORT levels relative to later migrating birds, there was also a disassociation between plasma and feather CORT, and blood parasite loads. These results demonstrate how these tissues integrate time periods from weeks to seasons and reflect energetic demands during differing life stages. Taken together, these findings illustrate the potential for integrating diverse biomarkers to assess interactions between environmental factors and animal health across varied time periods without the necessity of continually recapturing and tracking individuals. Combining biomarkers from diverse research fields into an integrated framework hold great promise for advancing our understanding of environmental effects on animal health.

Critical disease windows shaped by stress exposure alter allocation trade‐offs between development and immunity

“…#501320). These kits were validated using pooled samples for serial dilutions and quantitative recovery (Gabor & Bosch, 2013;Warne, Proudfoot, & Crespi, 2015). A dilution of 1:5 provided an optimal detection range where the serial dilution was parallel to a standard curve (ANCOVA slope comparison; F 1,6 = 3.1, p = .13).…”

Haemosporidian prevalence in northern saw‐whet owls Aegolius acadicus is predicted by host age and average annual temperature at breeding grounds

“…Across all years, banding day number was defined starting with 1 October as banding day 1, continuing sequentially until the latest capture day of 6 December, banding day 67; thus a banding day of 32, for example, would correspond to 1 November in any year. Warne et al (2015) used an integrative approach that included assay of deuterium (δD) isotope in feathers and corticosterone profiles in blood and feathers to test for associations between blood parasite levels, geographic location, and long and short-term stress in saw-whet owls in varied ecological conditions. The isotope map presented in that study was generated from δD values of HY saw-whet owls (n = 58) sampled on the Mohonk Preserve in 2011, samples which were included in our molecular analysis.…”

“…The isotope map presented in that study was generated from δD values of HY saw-whet owls (n = 58) sampled on the Mohonk Preserve in 2011, samples which were included in our molecular analysis. Capitalizing on this research overlap, we used the δD isotope map from Warne et al (2015) to estimate the location of breeding grounds of the owls included in this study (Fig. 1a).…”

“…Average annual temperature (a), total annual precipitation (b), and total days with > 2.54 cm of snow depth (c) determined from data provided by NOAA weather stations located within the proposed northern saw-whet owl breeding grounds established from stable isotope analysis(Warne et al 2015).…”

Physiological predictors of reproductive performance in the European Starling (Sturnus vulgaris): I. Univariate analysis

“…In this paper, we present univariate analyses in order to test biologically intuitive hypotheses, as well as facilitate interpretation of the relationships. However, there is a growing recognition of the complex and integrative nature of physiological systems (37, 40, 41). In a companion paper (Cohen et al, submitted) we explore the utility of analysing the same data set using multivariate analysis (Principal Components Analysis, Mahalanobis distance) to account for potentially complex physiological integration.…”