title: Baseline corticosterone and stress response in the Thorn-tailed Rayadito (Aphrastura spinicauda) along a latitudinal gradient.
abstract: Glucocorticoids are essential for life and their secretion is regulated by the hypothalamic-pituitary-adrenal axis (HPA). The HPA axis is often divided into two components: baseline glucocorticoids levels and stress response glucocorticoids levels, which are affected by changes in ambient temperature and productivity among others factors. An approximation to evaluate how a species copes with these changes is to evaluate differences of this hormone amongst populations of the same species that inhabit places ideally presenting all the possible combinations of temperature and productivity. We aimed to evaluate whether environmental temperature or productivity, represent challenges in terms of stress in the Thorn-tailed Rayadito (Aphrastura spinicauda). We examined circulating baseline levels of CORT and stress responses from three populations, covering the whole geographic distribution of the species across large gradients in weather conditions. If low temperature influences baseline CORT levels, we expect higher levels of this hormone in the southernmost population (higher latitude). However, if productivity is the factor that influences baseline CORT levels, we expect the contrary pattern, that is, lower values of this hormone in the southernmost population (more productive environment). We observed that baseline CORT levels presented lower values in the southernmost population, supporting the environmental productivity hypothesis. Secondly, we tested the hypothesis that individuals breeding at higher latitudes should have a lower stress response than individuals breeding at lower latitudes. Contrary to our expectations, we found that stress response did not vary among populations in any of the three years. We concluded that low environmental temperatures did not represent a stress situation for the Thorn-tailed Rayadito if food abundance was sufficient to support energetic demands.
authors.affiliation: Instituto de Ecología y Biodiversidad & Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile. Electronic address: veronica.quirici@uchile.cl.
authors.forename: Verónica
authors.initials: V
authors.lastname: Quirici
authors.affiliation: Instituto de Ecología y Biodiversidad & Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile.
authors.forename: Cristóbal I
authors.initials: CI
authors.lastname: Venegas
authors.affiliation: Department of Neurobiology, Physiology and Behavior, University of California, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Paulina L
authors.initials: PL
authors.lastname: González-Gómez
authors.affiliation: Instituto de Ecología y Biodiversidad & Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile.
authors.forename: Gabriel J
authors.initials: GJ
authors.lastname: Castaño-Villa
authors.affiliation: Department of Neurobiology, Physiology and Behavior, University of California, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Wingfield
authors.affiliation: Instituto de Ecología y Biodiversidad & Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Vásquez
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000097:blood*; D057231:Climate Change; D003345:Corticosterone / Q000097:blood*; D004777:Environment; D046109:Passeriformes / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D013696:Temperature
chemical_list: D000893:Anti-Inflammatory Agents; D003345:Corticosterone
keywords: Environmental productivity; Furnariidae; Geographic range; Southern hemisphere